# Surgical-mask recommendation × Infection in the wearer at one month

Verdict 2971 · Evidence Check

Stored-material review date: Not recorded  
Original evidence cut-off: 2026-08-26  
Review-criteria version: 1.0  
Public page/material preparation date: 2026-10-14

Clinical papers were not read directly; existing review summaries were checked. No new clinical-literature search was performed. Unverified does not mean that research is absent or that there is no effect.

## Assessment scope

- Population: Adults in 2020 Denmark where community mask use was uncommon. Distinguish 6,024 randomized (3,030/2,994) from 4,862 primary complete cases (2,392/2,470), with 19.3% missingness. Baseline risk/infection, recruitment/testing and missingness/dropout details remain unverified.
- Ingredient, formulation and route: Research intervention supplying a surgical-mask recommendation, 50 masks and instructions. Actual supply/wearing, specifications/batches and exposure/contacts remain unverified. It is not relabeled as filtration/product effects alone or mandate effects. No new wearing/testing/infection-prevention instructions.
- Dose: One-month recommendation/follow-up. Preserve self-reported 46% adherence as recommended, 47% predominantly as recommended and 7% nonadherence; do not fill objective wearing time, complete follow-up for all or other-period/long-term exposure.
- Comparator: Unblinded randomized comparison with both groups following prevailing public-health advice. Control is not relabeled as no action/contact or identical conditions. Actual control wearing/concurrent exposure and allocation/adjudication/analysis details remain unverified.
- Measured outcome: Primary composite of the wearer’s own SARS-CoV-2 infection at one month by antibody testing, PCR or hospital diagnosis. Preserve separate original estimands: 42/2,392(1.8%) versus 53/2,470(2.1%); absolute difference −0.3 percentage points (95% CI −1.2–0.4)/P=.38; OR 0.82(0.54–1.23)/P=.33. Component counts/tests, overlap, baseline/assessment windows and models remain unverified. No new RR/effects/CI or event/proportion totals.
- Duration: One-month wearer outcome. Individual actual exposure/observations, testing windows/repetition, later follow-up, other epidemics/healthcare settings and long-term effects remain unverified.
- Questions outside this scope: New differences/RR/NNT/CI or event/denominator totals from 42/2,392, 53/2,470 or 1.8/2.1%; Combining the original absolute-difference/OR P values and intervals as one estimand, or converting OR to RR/individual risk; Replacing recommendation/50 masks/instructions or 46/47/7% reports with objective full wearing or product/filtration effects alone; Relabeling 4,862 complete cases/19.3% missingness as ITT for all 6,024 or no missing-data effects; Transferring antibody/PCR/hospital-diagnosis composite infection to PCR alone, self-reported symptoms, transmission to others or mandates; Generalizing 2020 Danish one-month recommendations to current epidemics, healthcare, long-term use or all masks; Changing original six-day retrospective registration into prospective registration, fully verified prespecification or definite outcome switching; Summing people/groups/tests/events/timepoints/bibliographies, registrations or sibling sheets as new independent trials/participants; Inheriting original parent values/axes or historical verification/registration/allocation/masking/analysis wording as subclaim scores or current content review/full-text reading; New calculations, invented quantities, effects/CI, grades, independence certification or mask/testing/infection-prevention/respiratory-care/treatment-replacement instructions

## Checklist items

### N01 · Selected wearer question and original grade

Verification status: Partly verified  
Reading scope: Summary read; external material unread

- Current findings: The selected subclaim is “Reduced infection in the wearer at one month,” grade D with the null OR 0.82(0.54–1.23) note. Subclaim score/status/axes are absent; parent D34 is not used to fill a subclaim score.
- Why unverified: Only corresponding preserved-summary information is recorded; detailed original materials remain unread and existing content review is incomplete. Absent subclaim score/status/axes are distinguished from transmission-to-others and mandate effects. Existing content review remains incomplete.
- Reason for missing information: Absent subclaim score/status/axes are distinguished from transmission-to-others and mandate effects.
- Required materials and conditions: Existing question, grade/note, parent values and separate transmission question
- Materials to obtain first: Original selected-subclaim/parent records and user correction comments
- Further research: Proposal for later research specifying the wearer endpoint/timepoint; no new investigation, calculation or trial was performed in that production.
- Conditions for verification: Corresponding original materials and analysis scope for existing question, grade/note, parent values and separate transmission question should be available, with unverified matters distinguishable. Preserved wording is connected here; existing content review remains incomplete.
- Why this condition is needed: Applicability item distinguishing existing question, grade/note, parent values and separate transmission question and connecting materials needed for the selected question with current materials.
- Application exceptions: Limited to the stored summary for the selected formulation, population, endpoint and period. It does not substitute for numbers from other formulations/trials/endpoints or unread external material.
- Remaining uncertainty: This record links preserved-summary statements; it does not establish external-paper comparison, a new efficacy verdict or completed content review.
- Referenced methods: M03 §3.1, §3.2.1–3.2.4 question-clarification principles; detailed separation rules are custom design; M03 §3.2.4, M15 §15.3.1–15.3.3; question-specific outcome adaptation is custom design; M04 §4.5, §4.6.3; limits on current material conversion reflect the review scope and custom design
- Related sources: S01

### N02 · 2020 Denmark and community setting

Verification status: Partly verified  
Reading scope: Summary read; external material unread

- Current findings: DANMASK-19 studied adults in 2020 Denmark where community mask use was uncommon. Results are not extended to current/other epidemics, healthcare settings or protection of all populations.
- Why unverified: Only corresponding preserved-summary information is recorded; detailed original materials remain unread and existing content review is incomplete. Age/eligibility, baseline infection/risk, exposure/occupation, recruitment/group balance and test access remain unverified. Existing content review remains incomplete.
- Reason for missing information: Age/eligibility, baseline infection/risk, exposure/occupation, recruitment/group balance and test access remain unverified.
- Required materials and conditions: Time/setting, actual population, recruitment and baseline risk
- Materials to obtain first: Population/recruitment, baseline-risk and setting tables
- Further research: Proposal for later comparative research specifying the setting/population; no new investigation, calculation or trial was performed in that production.
- Conditions for verification: Corresponding original materials and analysis scope for time/setting, actual population, recruitment and baseline risk should be available, with unverified matters distinguishable. Preserved wording is connected here; existing content review remains incomplete.
- Why this condition is needed: Applicability item distinguishing time/setting, actual population, recruitment and baseline risk and connecting materials needed for the selected question with current materials.
- Application exceptions: Limited to the stored summary for the selected formulation, population, endpoint and period. It does not substitute for numbers from other formulations/trials/endpoints or unread external material.
- Remaining uncertainty: This record links preserved-summary statements; it does not establish external-paper comparison, a new efficacy verdict or completed content review.
- Referenced methods: M03 §3.2.1; Detailed population conditions are Chamgap design; M03 §3.2.1–3.2.4; Dose, duration and effect-modifier details are Chamgap design
- Related sources: S01

### N03 · Recommendation, 50 masks and instructions

Verification status: Partly verified  
Reading scope: Summary read; external material unread

- Current findings: The intervention supplied a surgical-mask recommendation, 50 masks and instructions. It is not relabeled as full actual wearing, filtration/product effects alone or a mandate trial.
- Why unverified: Only corresponding preserved-summary information is recorded; detailed original materials remain unread and existing content review is incomplete. Product specifications/batches, actual supply/instructions, additional contacts and wearing conditions/exposure remain unverified. Existing content review remains incomplete.
- Reason for missing information: Product specifications/batches, actual supply/instructions, additional contacts and wearing conditions/exposure remain unverified.
- Required materials and conditions: Assigned recommendation/support versus actual wearing and product effects
- Materials to obtain first: Recommendation/supply/instruction, product and contact records
- Further research: Proposal for later research distinguishing recommendation/support from actual wearing; no new investigation, calculation or trial was performed in that production.
- Conditions for verification: Corresponding original materials and analysis scope for assigned recommendation/support versus actual wearing and product effects should be available, with unverified matters distinguishable. Preserved wording is connected here; existing content review remains incomplete.
- Why this condition is needed: Applicability item distinguishing assigned recommendation/support versus actual wearing and product effects and connecting materials needed for the selected question with current materials.
- Application exceptions: Limited to the stored summary for the selected formulation, population, endpoint and period. It does not substitute for numbers from other formulations/trials/endpoints or unread external material.
- Remaining uncertainty: This record links preserved-summary statements; it does not establish external-paper comparison, a new efficacy verdict or completed content review.
- Referenced methods: M03 §3.2.2–3.2.3; Reverse-direction labels and assessment adaptation are Chamgap design; M03 §3.2.3 and M08 §8.2.2–8.2.3; Chamgap application
- Related sources: S01

### N04 · Actual wearing and self-reported adherence

Verification status: Partly verified  
Reading scope: Summary read; external material unread

- Current findings: Preserve self-reported adherence: 46% as recommended, 47% predominantly as recommended, 7% not as recommended. These do not fill objective wearing-time/precise exposure records for all participants.
- Why unverified: Only corresponding preserved-summary information is recorded; detailed original materials remain unread and existing content review is incomplete. Adherence-questionnaire denominators/timing/definitions, objective wearing/use, missingness and group crossover remain unverified. Existing content review remains incomplete.
- Reason for missing information: Adherence-questionnaire denominators/timing/definitions, objective wearing/use, missingness and group crossover remain unverified.
- Required materials and conditions: 46/47/7% categories/periods, measurement and exposure
- Materials to obtain first: Adherence questionnaires/denominators and actual wearing/exposure
- Further research: Proposal specifying differences between reported adherence and actual exposure; no new investigation, calculation or trial was performed in that production.
- Conditions for verification: Corresponding original materials and analysis scope for 46/47/7% categories/periods, measurement and exposure should be available, with unverified matters distinguishable. Preserved wording is connected here; existing content review remains incomplete.
- Why this condition is needed: Applicability item distinguishing 46/47/7% categories/periods, measurement and exposure and connecting materials needed for the selected question with current materials.
- Application exceptions: Limited to the stored summary for the selected formulation, population, endpoint and period. It does not substitute for numbers from other formulations/trials/endpoints or unread external material.
- Remaining uncertainty: This record links preserved-summary statements; it does not establish external-paper comparison, a new efficacy verdict or completed content review.
- Referenced methods: M03 §3.2.3, M08 §8.2.2–8.2.3; own application; M08 Table 8.2.a, M03 §3.2.4; own application; M08 Table 8.2.a, M15 §15.3, M19 §19.1.2–19.2.4; design-specific adaptation is independently designed
- Related sources: S01

### N05 · Recommendation effects and adherence-based analysis

Verification status: Partly verified  
Reading scope: Summary read; external material unread

- Current findings: The original trial compares assigned recommendations. The original low-full-adherence context is retained without newly estimating actual-wearer/full-adherence effects or certifying benefits.
- Why unverified: Only corresponding preserved-summary information is recorded; detailed original materials remain unread and existing content review is incomplete. Prespecified adherence-based plans, inclusion/exposure, adjustment/confounding and related sensitivity results remain unverified. Existing content review remains incomplete.
- Reason for missing information: Prespecified adherence-based plans, inclusion/exposure, adjustment/confounding and related sensitivity results remain unverified.
- Required materials and conditions: Assigned recommendation versus actual-wearer/full-adherence effects
- Materials to obtain first: Recommendation/adherence analysis plans, models and original results
- Further research: Proposal distinguishing assignment strategies and actual-exposure estimands; no new investigation, calculation or trial was performed in that production.
- Conditions for verification: Corresponding original materials and analysis scope for assigned recommendation versus actual-wearer/full-adherence effects should be available, with unverified matters distinguishable. Preserved wording is connected here; existing content review remains incomplete.
- Why this condition is needed: Applicability item distinguishing assigned recommendation versus actual-wearer/full-adherence effects and connecting materials needed for the selected question with current materials.
- Application exceptions: Limited to the stored summary for the selected formulation, population, endpoint and period. It does not substitute for numbers from other formulations/trials/endpoints or unread external material.
- Remaining uncertainty: This record links preserved-summary statements; it does not establish external-paper comparison, a new efficacy verdict or completed content review.
- Referenced methods: M08 §8.2.2, M15 §15.3.1; own application; M03 §3.2.3, M08 §8.2.2–8.2.3; own application; M08 Table 8.2.a, M04 §4.6.3; own application
- Related sources: S01

### N06 · Control and concurrent public-health measures

Verification status: Partly verified  
Reading scope: Summary read; external material unread

- Current findings: Both groups followed prevailing public-health advice. This does not verify a no-action/no-contact control or identical prevention/lifestyle/exposure conditions.
- Why unverified: Only corresponding preserved-summary information is recorded; detailed original materials remain unread and existing content review is incomplete. Control mask wearing/additional support, concurrent measures, lifestyle/exposure, contacts and differences/analyses remain unverified. Existing content review remains incomplete.
- Reason for missing information: Control mask wearing/additional support, concurrent measures, lifestyle/exposure, contacts and differences/analyses remain unverified.
- Required materials and conditions: Actual measures and contact/exposure differences across groups
- Materials to obtain first: Control/concurrent measures, wearing/exposure and contact records
- Further research: Proposal specifying actual comparisons/concurrent conditions; no new investigation, calculation or trial was performed in that production.
- Conditions for verification: Corresponding original materials and analysis scope for actual measures and contact/exposure differences across groups should be available, with unverified matters distinguishable. Preserved wording is connected here; existing content review remains incomplete.
- Why this condition is needed: Applicability item distinguishing actual measures and contact/exposure differences across groups and connecting materials needed for the selected question with current materials.
- Application exceptions: Limited to the stored summary for the selected formulation, population, endpoint and period. It does not substitute for numbers from other formulations/trials/endpoints or unread external material.
- Remaining uncertainty: This record links preserved-summary statements; it does not establish external-paper comparison, a new efficacy verdict or completed content review.
- Referenced methods: M03 §3.2.2–3.2.3; Reverse-direction labels and assessment adaptation are Chamgap design; M03 §3.2.3 and M08 §8.2.2–8.2.3; Chamgap application
- Related sources: S01

### N07 · Randomization and lack of masking

Verification status: Partly verified  
Reading scope: Summary read; external material unread

- Current findings: The original design is a nationwide unblinded randomized controlled trial. The randomization label does not verify all sequence/concealment or test/adjudicator/analyst masking details.
- Why unverified: Only corresponding preserved-summary information is recorded; detailed original materials remain unread and existing content review is incomplete. Original sequence generation/concealment, implementation/exceptions, role-specific masking and baseline balance remain unread. Existing content review remains incomplete.
- Reason for missing information: Original sequence generation/concealment, implementation/exceptions, role-specific masking and baseline balance remain unread.
- Required materials and conditions: Design label and scope of allocation/measurement/analysis procedures
- Materials to obtain first: Original allocation/concealment, masking roles, baseline and protocol materials
- Further research: Proposal disclosing allocation and outcome measurement/adjudication; no new investigation, calculation or trial was performed in that production.
- Conditions for verification: Corresponding original materials and analysis scope for design label and scope of allocation/measurement/analysis procedures should be available, with unverified matters distinguishable. Preserved wording is connected here; existing content review remains incomplete.
- Why this condition is needed: Applicability item distinguishing design label and scope of allocation/measurement/analysis procedures and connecting materials needed for the selected question with current materials.
- Application exceptions: Limited to the stored summary for the selected formulation, population, endpoint and period. It does not substitute for numbers from other formulations/trials/endpoints or unread external material.
- Remaining uncertainty: This record links preserved-summary statements; it does not establish external-paper comparison, a new efficacy verdict or completed content review.
- Referenced methods: M08 §§8.1–8.2.3; Chamgap adaptation; M08 Table 8.2.a and M03 §3.2.4; Chamgap adaptation; M04 §§4.5–4.6 material collection/selection principles; access/reading separation and hyperlink rules are Chamgap-designed
- Related sources: S01

### N08 · Composite infection ascertainment

Verification status: Partly verified  
Reading scope: Summary read; external material unread

- Current findings: The primary endpoint is the wearer’s own SARS-CoV-2 infection at one month, ascertained through antibody testing, PCR or hospital diagnosis. It is not relabeled as PCR alone, self-reported symptoms or transmission to others.
- Why unverified: Only corresponding preserved-summary information is recorded; detailed original materials remain unread and existing content review is incomplete. Component definitions/tests, accepted results, overlap/adjudication and event timing remain unverified. Existing content review remains incomplete.
- Reason for missing information: Component definitions/tests, accepted results, overlap/adjudication and event timing remain unverified.
- Required materials and conditions: Antibody testing, PCR, hospital diagnosis and component/adjudication rules
- Materials to obtain first: Composite-endpoint definitions, testing/adjudication and component/overlap materials
- Further research: Proposal distinguishing component ascertainment from the composite endpoint; no new investigation, calculation or trial was performed in that production.
- Conditions for verification: Corresponding original materials and analysis scope for antibody testing, PCR, hospital diagnosis and component/adjudication rules should be available, with unverified matters distinguishable. Preserved wording is connected here; existing content review remains incomplete.
- Why this condition is needed: Applicability item distinguishing antibody testing, PCR, hospital diagnosis and component/adjudication rules and connecting materials needed for the selected question with current materials.
- Application exceptions: Limited to the stored summary for the selected formulation, population, endpoint and period. It does not substitute for numbers from other formulations/trials/endpoints or unread external material.
- Remaining uncertainty: This record links preserved-summary statements; it does not establish external-paper comparison, a new efficacy verdict or completed content review.
- Referenced methods: M03 §3.2.4, M15 §15.3.1–15.3.3; question-specific outcome adaptations are internally designed; M08 Table 8.2.a, M03 §3.2.4; internal application; M08 §8.2.2, M15 §15.3.1; internal application
- Related sources: S01

### N09 · Testing time, baseline infection and missingness

Verification status: Partly verified  
Reading scope: Summary read; external material unread

- Current findings: Preserve the original ascertainment methods and one-month period without claiming verified test counts, baseline status, assessment windows or identical ascertainment of all events.
- Why unverified: Only corresponding preserved-summary information is recorded; detailed original materials remain unread and existing content review is incomplete. Baseline infection, test/sample timing, implementation/nonimplementation, access, adjudication/errors and confirmation delays remain unverified. Existing content review remains incomplete.
- Reason for missing information: Baseline infection, test/sample timing, implementation/nonimplementation, access, adjudication/errors and confirmation delays remain unverified.
- Required materials and conditions: Correspondence of one-month infection with tests/baseline/assessment windows
- Materials to obtain first: Testing/baseline/assessment flow and adjudication/missingness materials
- Further research: Proposal specifying testing/baseline conditions and infection-adjudication timing; no new investigation, calculation or trial was performed in that production.
- Conditions for verification: Corresponding original materials and analysis scope for correspondence of one-month infection with tests/baseline/assessment windows should be available, with unverified matters distinguishable. Preserved wording is connected here; existing content review remains incomplete.
- Why this condition is needed: Applicability item distinguishing correspondence of one-month infection with tests/baseline/assessment windows and connecting materials needed for the selected question with current materials.
- Application exceptions: Limited to the stored summary for the selected formulation, population, endpoint and period. It does not substitute for numbers from other formulations/trials/endpoints or unread external material.
- Remaining uncertainty: This record links preserved-summary statements; it does not establish external-paper comparison, a new efficacy verdict or completed content review.
- Referenced methods: M08 Table 8.2.a, M03 §3.2.4; own application; M03 §3.2.4, M15 §15.3.1–15.3.3; question-specific outcome adaptation is independently designed; M08 Table 8.2.a, M15 §15.3, M19 §19.1.2–19.2.4; design-specific adaptation is independently designed
- Related sources: S01

### N10 · One month and duration/exposure scope

Verification status: Partly verified  
Reading scope: Summary read; external material unread

- Current findings: Follow-up was one month. The same recommendation is not expanded to sustained long-term/other-epidemic/healthcare/other-mask effects, and no use/testing instructions are produced.
- Why unverified: Only corresponding preserved-summary information is recorded; detailed original materials remain unread and existing content review is incomplete. Individual observation/wearing periods, start/end/censoring and later follow-up/exposure remain unverified. Existing content review remains incomplete.
- Reason for missing information: Individual observation/wearing periods, start/end/censoring and later follow-up/exposure remain unverified.
- Required materials and conditions: Original period, actual observation/wearing and long-term/other-epidemic boundaries
- Materials to obtain first: Period/visit, actual exposure and long-term follow-up materials
- Further research: Proposal distinguishing timepoint/duration and setting-specific applicability; no new investigation, calculation or trial was performed in that production.
- Conditions for verification: Corresponding original materials and analysis scope for original period, actual observation/wearing and long-term/other-epidemic boundaries should be available, with unverified matters distinguishable. Preserved wording is connected here; existing content review remains incomplete.
- Why this condition is needed: Applicability item distinguishing original period, actual observation/wearing and long-term/other-epidemic boundaries and connecting materials needed for the selected question with current materials.
- Application exceptions: Limited to the stored summary for the selected formulation, population, endpoint and period. It does not substitute for numbers from other formulations/trials/endpoints or unread external material.
- Remaining uncertainty: This record links preserved-summary statements; it does not establish external-paper comparison, a new efficacy verdict or completed content review.
- Referenced methods: M03 §3.2.4, M15 §15.3.1–15.3.3; question-specific outcome adaptations are internally designed; M03 §3.2.1–3.2.4; dose, duration and effect-modification details are internally designed
- Related sources: S01

### N11 · Original events and complete-case denominators

Verification status: Partly verified  
Reading scope: Summary read; external material unread

- Current findings: Primary results were 42/2,392(1.8%) versus 53/2,470(2.1%). They are not relabeled with all-randomized denominators, test counts or total repeated infections; no new proportions/event totals are calculated.
- Why unverified: Only corresponding preserved-summary information is recorded; detailed original materials remain unread and existing content review is incomplete. Component-specific event counts, test/person overlap, risk/observation denominators and ascertainment-method correspondence remain unverified. Existing content review remains incomplete.
- Reason for missing information: Component-specific event counts, test/person overlap, risk/observation denominators and ascertainment-method correspondence remain unverified.
- Required materials and conditions: 42/2,392 and 53/2,470 versus people/test units
- Materials to obtain first: Original events/components, denominators/tests and observations
- Further research: Proposal reporting people/events/tests and denominators separately; no new investigation, calculation or trial was performed in that production.
- Conditions for verification: Corresponding original materials and analysis scope for 42/2,392 and 53/2,470 versus people/test units should be available, with unverified matters distinguishable. Preserved wording is connected here; existing content review remains incomplete.
- Why this condition is needed: Applicability item distinguishing 42/2,392 and 53/2,470 versus people/test units and connecting materials needed for the selected question with current materials.
- Application exceptions: Limited to the stored summary for the selected formulation, population, endpoint and period. It does not substitute for numbers from other formulations/trials/endpoints or unread external material.
- Remaining uncertainty: This record links preserved-summary statements; it does not establish external-paper comparison, a new efficacy verdict or completed content review.
- Referenced methods: M08 Table 8.2.a, M15 §15.3 and M19 §19.1.2–19.2.4; Design-specific adaptation is Chamgap design; M08 §8.2.2 and M15 §15.3.1; Chamgap application; M15 §15.3.1–15.3.3; Chamgap application
- Related sources: S01

### N12 · Original absolute difference, CI and P

Verification status: Partly verified  
Reading scope: Summary read; external material unread

- Current findings: Preserve absolute difference −0.3 percentage points (95% CI −1.2–0.4), P=.38. Do not newly subtract 1.8%/2.1% or calculate a new effect, CI or NNT.
- Why unverified: Only corresponding preserved-summary information is recorded; detailed original materials remain unread and existing content review is incomplete. Exact contrasts/models, adjustment, CI methods and original plans/sensitivity remain unread. Existing content review remains incomplete.
- Reason for missing information: Exact contrasts/models, adjustment, CI methods and original plans/sensitivity remain unread.
- Required materials and conditions: Original absolute effect/CI versus rounded proportions and models
- Materials to obtain first: Original absolute effects/models, CI and prespecified plans
- Further research: Proposal for later research disclosing effect measures and precision; no new investigation, calculation or trial was performed in that production.
- Conditions for verification: Corresponding original materials and analysis scope for original absolute effect/CI versus rounded proportions and models should be available, with unverified matters distinguishable. Preserved wording is connected here; existing content review remains incomplete.
- Why this condition is needed: Applicability item distinguishing original absolute effect/CI versus rounded proportions and models and connecting materials needed for the selected question with current materials.
- Application exceptions: Limited to the stored summary for the selected formulation, population, endpoint and period. It does not substitute for numbers from other formulations/trials/endpoints or unread external material.
- Remaining uncertainty: This record links preserved-summary statements; it does not establish external-paper comparison, a new efficacy verdict or completed content review.
- Referenced methods: M15 §15.3.1–15.3.3; internal application; M08 §8.2.2, M15 §15.3.1; internal application; M08 Table 8.2.a, M15 §15.3, M19 §19.1.2–19.2.4; design-specific adaptations are internally designed.
- Related sources: S01

### N13 · OR, CI and separate P

Verification status: Partly verified  
Reading scope: Summary read; external material unread

- Current findings: OR 0.82(0.54–1.23), P=.33 is the original result. It is retained separately from absolute-difference P=.38; OR is not converted to RR, individual risk or a new relative reduction.
- Why unverified: Only corresponding preserved-summary information is recorded; detailed original materials remain unread and existing content review is incomplete. OR models/adjustment, precise contrasts, tests/CI methods and correspondence to absolute effects remain unread. Existing content review remains incomplete.
- Reason for missing information: OR models/adjustment, precise contrasts, tests/CI methods and correspondence to absolute effects remain unread.
- Required materials and conditions: Original OR/CI versus the different absolute-difference estimand
- Materials to obtain first: OR/absolute-effect models/tests and original results
- Further research: Proposal reporting effect measures/tests separately; no new investigation, calculation or trial was performed in that production.
- Conditions for verification: Corresponding original materials and analysis scope for original OR/CI versus the different absolute-difference estimand should be available, with unverified matters distinguishable. Preserved wording is connected here; existing content review remains incomplete.
- Why this condition is needed: Applicability item distinguishing original OR/CI versus the different absolute-difference estimand and connecting materials needed for the selected question with current materials.
- Application exceptions: Limited to the stored summary for the selected formulation, population, endpoint and period. It does not substitute for numbers from other formulations/trials/endpoints or unread external material.
- Remaining uncertainty: This record links preserved-summary statements; it does not establish external-paper comparison, a new efficacy verdict or completed content review.
- Referenced methods: M15 §15.3.1–15.3.3; internal application; M08 §8.2.2, M15 §15.3.1; internal application; M08 Table 8.2.a, M15 §15.3, M19 §19.1.2–19.2.4; design-specific adaptations are internally designed.
- Related sources: S01

### N14 · Nonsignificance, wide CI and importance

Verification status: Partly verified  
Reading scope: Summary read; external material unread

- Current findings: The original manuscript records no established primary benefit and a CI retaining substantial benefit/harm possibilities. It is not changed to zero effect, equivalence or confirmed general mask ineffectiveness/harm.
- Why unverified: Only corresponding preserved-summary information is recorded; detailed original materials remain unread and existing content review is incomplete. Prespecified importance/success/equivalence criteria and sufficient precision for exact effects remain unverified. Existing content review remains incomplete.
- Reason for missing information: Prespecified importance/success/equivalence criteria and sufficient precision for exact effects remain unverified.
- Required materials and conditions: Null verdict versus possible benefit/harm, exactly zero and equivalence
- Materials to obtain first: Prespecified criteria, models/CI and estimand materials
- Further research: Proposal specifying effects/precision and question scope; no new investigation, calculation or trial was performed in that production.
- Conditions for verification: Corresponding original materials and analysis scope for null verdict versus possible benefit/harm, exactly zero and equivalence should be available, with unverified matters distinguishable. Preserved wording is connected here; existing content review remains incomplete.
- Why this condition is needed: Applicability item distinguishing null verdict versus possible benefit/harm, exactly zero and equivalence and connecting materials needed for the selected question with current materials.
- Application exceptions: Limited to the stored summary for the selected formulation, population, endpoint and period. It does not substitute for numbers from other formulations/trials/endpoints or unread external material.
- Remaining uncertainty: This record links preserved-summary statements; it does not establish external-paper comparison, a new efficacy verdict or completed content review.
- Referenced methods: M15 §15.3.1–15.3.3; in-house application; M04 §4.6.3, M15 §15.3.1–15.3.3; status separation is in-house design; M03 §3.2.4; in-house extension boundaries
- Related sources: S01

### N15 · 6,024 randomized and 4,862 complete cases

Verification status: Partly verified  
Reading scope: Summary read; external material unread

- Current findings: Preserve 6,024 randomized (3,030/2,994) and 4,862 primary complete cases (2,392/2,470). These populations/group counts are not combined or filled as complete observation/ITT for everyone.
- Why unverified: Only corresponding preserved-summary information is recorded; detailed original materials remain unread and existing content review is incomplete. Complete-case inclusion/exclusion, test/component-specific valid denominators and baseline/visit correspondence remain unverified. Existing content review remains incomplete.
- Reason for missing information: Complete-case inclusion/exclusion, test/component-specific valid denominators and baseline/visit correspondence remain unverified.
- Required materials and conditions: Randomized/complete-case populations and group denominators
- Materials to obtain first: Flow, analysis-population definitions and endpoint/test denominators
- Further research: Proposal distinguishing allocated/observed/analyzed denominators; no new investigation, calculation or trial was performed in that production.
- Conditions for verification: Corresponding original materials and analysis scope for randomized/complete-case populations and group denominators should be available, with unverified matters distinguishable. Preserved wording is connected here; existing content review remains incomplete.
- Why this condition is needed: Applicability item distinguishing randomized/complete-case populations and group denominators and connecting materials needed for the selected question with current materials.
- Application exceptions: Limited to the stored summary for the selected formulation, population, endpoint and period. It does not substitute for numbers from other formulations/trials/endpoints or unread external material.
- Remaining uncertainty: This record links preserved-summary statements; it does not establish external-paper comparison, a new efficacy verdict or completed content review.
- Referenced methods: M08 Table 8.2.a, M15 §15.3 and M19 §19.1.2–19.2.4; Design-specific adaptation is Chamgap design; M08 §8.2.2 and M15 §15.3.1; Chamgap application
- Related sources: S01

### N16 · 19.3% missingness and dropout

Verification status: Partly verified  
Reading scope: Summary read; external material unread

- Current findings: Primary missingness 19.3% is the original record. No new missing counts/rates or best/worst effects are calculated, and absence of missing-data effects is not certified.
- Why unverified: Only corresponding preserved-summary information is recorded; detailed original materials remain unread and existing content review is incomplete. Original group missingness/dropout reasons, baseline risk, test/contact differences and handling/sensitivity remain unverified. Existing content review remains incomplete.
- Reason for missing information: Original group missingness/dropout reasons, baseline risk, test/contact differences and handling/sensitivity remain unverified.
- Required materials and conditions: Group missingness/deviations, testing/reporting and outcome effects
- Materials to obtain first: Group flow, missingness/contact, missing-data handling and sensitivity
- Further research: Proposal reporting effects of missingness and observation selection; no new investigation, calculation or trial was performed in that production.
- Conditions for verification: Corresponding original materials and analysis scope for group missingness/deviations, testing/reporting and outcome effects should be available, with unverified matters distinguishable. Preserved wording is connected here; existing content review remains incomplete.
- Why this condition is needed: Applicability item distinguishing group missingness/deviations, testing/reporting and outcome effects and connecting materials needed for the selected question with current materials.
- Application exceptions: Limited to the stored summary for the selected formulation, population, endpoint and period. It does not substitute for numbers from other formulations/trials/endpoints or unread external material.
- Remaining uncertainty: This record links preserved-summary statements; it does not establish external-paper comparison, a new efficacy verdict or completed content review.
- Referenced methods: M08 Table 8.2.a, M15 §15.3, M19 §19.1.2–19.2.4; design-specific adaptation is independently designed; M08 §8.2.2, M15 §15.3.1; own application; M08 Table 8.2.a, M03 §3.2.4; own application
- Related sources: S01

### N17 · Complete-case estimands and within/between-group comparisons

Verification status: Partly verified  
Reading scope: Summary read; external material unread

- Current findings: The original primary analysis is complete-case. It is not relabeled as ITT for all randomized participants or actual full-wearing effects, and within-group improvements are not made into new between-group benefits.
- Why unverified: Only corresponding preserved-summary information is recorded; detailed original materials remain unread and existing content review is incomplete. Complete-case models/adjustment, observation selection, missingness/adherence sensitivity and other analyses remain unverified. Existing content review remains incomplete.
- Reason for missing information: Complete-case models/adjustment, observation selection, missingness/adherence sensitivity and other analyses remain unverified.
- Required materials and conditions: Analysis populations/models, assigned effects and observation selection
- Materials to obtain first: Analysis populations, models/contrasts and missingness/adherence sensitivity
- Further research: Proposal distinguishing assignment, observation and actual-exposure estimands; no new investigation, calculation or trial was performed in that production.
- Conditions for verification: Corresponding original materials and analysis scope for analysis populations/models, assigned effects and observation selection should be available, with unverified matters distinguishable. Preserved wording is connected here; existing content review remains incomplete.
- Why this condition is needed: Applicability item distinguishing analysis populations/models, assigned effects and observation selection and connecting materials needed for the selected question with current materials.
- Application exceptions: Limited to the stored summary for the selected formulation, population, endpoint and period. It does not substitute for numbers from other formulations/trials/endpoints or unread external material.
- Remaining uncertainty: This record links preserved-summary statements; it does not establish external-paper comparison, a new efficacy verdict or completed content review.
- Referenced methods: M08 §8.2.2, M15 §15.3.1; own application; M03 §3.2.3, M08 §8.2.2–8.2.3; own application; M08 Table 8.2.a, M15 §15.3, M19 §19.1.2–19.2.4; design-specific adaptation is independently designed
- Related sources: S01

### N18 · Registration, retrospective dates and plans

Verification status: Partly verified  
Reading scope: Summary read; external material unread

- Current findings: Original wording records NCT04337541 first posted 2020-04-08 after the 2020-04-02 start, six-day retrospective registration. It is not changed to prospective registration, verified complete prespecification or definite outcome switching.
- Why unverified: Only corresponding preserved-summary information is recorded; detailed original materials remain unread and existing content review is incomplete. Registration history, prerecruitment protocols/SAP, changes and complete endpoint/analysis contracts remain unread. Existing content review remains incomplete.
- Reason for missing information: Registration history, prerecruitment protocols/SAP, changes and complete endpoint/analysis contracts remain unread.
- Required materials and conditions: Preserved NCT/dates and prespecified endpoint/analysis contracts
- Materials to obtain first: Registration history, protocol, and SAP
- Further research: Proposal linking and disclosing plan/registration timing and actual analyses; no new investigation, calculation or trial was performed in that production.
- Conditions for verification: Corresponding original materials and analysis scope for preserved NCT/dates and prespecified endpoint/analysis contracts should be available, with unverified matters distinguishable. Preserved wording is connected here; existing content review remains incomplete.
- Why this condition is needed: Applicability item distinguishing preserved NCT/dates and prespecified endpoint/analysis contracts and connecting materials needed for the selected question with current materials.
- Application exceptions: Limited to the stored summary for the selected formulation, population, endpoint and period. It does not substitute for numbers from other formulations/trials/endpoints or unread external material.
- Remaining uncertainty: This record links preserved-summary statements; it does not establish external-paper comparison, a new efficacy verdict or completed content review.
- Referenced methods: M08 Table 8.2.a, M04 §4.6.3; custom application; M04 §4.5–4.6 material-collection/selection principles; separation of access/reading and hyperlink conventions are custom design; M04 §4.5, §4.6.3; limits on current material conversion reflect the review scope and custom design
- Related sources: S01

### N19 · Primary/secondary outcomes and multiplicity

Verification status: Partly verified  
Reading scope: Summary read; external material unread

- Current findings: The selected result is the wearer’s own one-month infection primary endpoint. Multiple tests, effect measures, adherence groups or other outcomes are not counted as independent trials or new primary successes.
- Why unverified: Only corresponding preserved-summary information is recorded; detailed original materials remain unread and existing content review is incomplete. Complete secondary/timepoint, multiplicity, testing-order, prespecified hierarchy and reporting changes remain unverified. Existing content review remains incomplete.
- Reason for missing information: Complete secondary/timepoint, multiplicity, testing-order, prespecified hierarchy and reporting changes remain unverified.
- Required materials and conditions: Wearer primary endpoint, test components and effect-measure/other-outcome hierarchy
- Materials to obtain first: SAP, complete outcomes and testing/hierarchy materials
- Further research: Proposal separating primary, component and secondary outcomes; no new investigation, calculation or trial was performed in that production.
- Conditions for verification: Corresponding original materials and analysis scope for wearer primary endpoint, test components and effect-measure/other-outcome hierarchy should be available, with unverified matters distinguishable. Preserved wording is connected here; existing content review remains incomplete.
- Why this condition is needed: Applicability item distinguishing wearer primary endpoint, test components and effect-measure/other-outcome hierarchy and connecting materials needed for the selected question with current materials.
- Application exceptions: Limited to the stored summary for the selected formulation, population, endpoint and period. It does not substitute for numbers from other formulations/trials/endpoints or unread external material.
- Remaining uncertainty: This record links preserved-summary statements; it does not establish external-paper comparison, a new efficacy verdict or completed content review.
- Referenced methods: M08 Table 8.2.a, M04 §4.6.3; own application; M04 §4.6.1–4.6.2 on distinguishing studies from reports; cohort/outcome linkage is independently applied; M03 §3.2.4, M15 §15.3.1–15.3.3; question-specific outcome adaptation is independently designed
- Related sources: S01

### N20 · Transmission to others and mandates were unmeasured

Verification status: Partly verified  
Reading scope: Summary read; external material unread

- Current findings: The original manuscript records that transmission prevention to others and mask-mandate effects were not tested. The selected wearer result is not transferred to their effects/null results or policy/procedural guidance.
- Why unverified: Only corresponding preserved-summary information is recorded; detailed original materials remain unread and existing content review is incomplete. Direct transmission-to-others, mandate, healthcare/other-epidemic results are not connected by this trial. Existing content review remains incomplete.
- Reason for missing information: Direct transmission-to-others, mandate, healthcare/other-epidemic results are not connected by this trial.
- Required materials and conditions: Wearer protection versus source control, policy and setting
- Materials to obtain first: Separate materials directly measuring those questions/settings
- Further research: Proposal for later research separating wearer/others/policy questions; no new investigation, calculation or trial was performed in that production.
- Conditions for verification: Corresponding original materials and analysis scope for wearer protection versus source control, policy and setting should be available, with unverified matters distinguishable. Preserved wording is connected here; existing content review remains incomplete.
- Why this condition is needed: Applicability item distinguishing wearer protection versus source control, policy and setting and connecting materials needed for the selected question with current materials.
- Application exceptions: Limited to the stored summary for the selected formulation, population, endpoint and period. It does not substitute for numbers from other formulations/trials/endpoints or unread external material.
- Remaining uncertainty: This record links preserved-summary statements; it does not establish external-paper comparison, a new efficacy verdict or completed content review.
- Referenced methods: M03 §3.1, §3.2.1–3.2.4 on clarifying questions; detailed separation rules are independently designed; M03 §3.2.4, M15 §15.3.1–15.3.3; question-specific outcome adaptation is independently designed; M03 §3.2.1–3.2.4; dose/duration/effect-modification details are independently designed
- Related sources: S01

### N21 · Concurrent measures, exposure and lifestyle

Verification status: Unverified  
Reading scope: Summary read; external material unread

- Current findings: Preserve the original prevailing-public-health-advice record for both groups without filling in identical/no-effect exposure, lifestyle/prevention or disease/medication conditions.
- Why unverified: Information currently required is unverified in the preserved summary. Concurrent measures, outside contacts/exposures, other masks/products, diseases/medications and group differences/analyses remain unverified. Existing content review remains incomplete.
- Reason for missing information: Concurrent measures, outside contacts/exposures, other masks/products, diseases/medications and group differences/analyses remain unverified.
- Required materials and conditions: Group concurrent prevention/exposure, diseases/medications and contacts
- Materials to obtain first: Concurrent conditions, exposures/contacts and analyses
- Further research: Proposal distinguishing concurrent conditions from recommendation/wearing effects; no new investigation, calculation or trial was performed in that production.
- Conditions for verification: Corresponding original materials and analysis scope for group concurrent prevention/exposure, diseases/medications and contacts should be available, with unverified matters distinguishable. Preserved wording is connected here; existing content review remains incomplete.
- Why this condition is needed: Applicability item distinguishing group concurrent prevention/exposure, diseases/medications and contacts and connecting materials needed for the selected question with current materials.
- Application exceptions: Limited to the stored summary for the selected formulation, population, endpoint and period. It does not substitute for numbers from other formulations/trials/endpoints or unread external material.
- Remaining uncertainty: This record links preserved-summary statements; it does not establish external-paper comparison, a new efficacy verdict or completed content review.
- Referenced methods: M03 §3.2.3, M08 §8.2.2–8.2.3; own application; M03 §3.2.2–3.2.3; reverse-direction labels and test adaptations are our own design
- Related sources: S01

### N22 · Salling funding and Rigshospitalet

Verification status: Partly verified  
Reading scope: Summary read; external material unread

- Current findings: Salling Foundations funding and Rigshospitalet leadership are original records. Institution/leadership names are not changed to absence of all support/relationships or new independence certification.
- Why unverified: Only corresponding preserved-summary information is recorded; detailed original materials remain unread and existing content review is incomplete. Original support/leadership roles, contracts, data/analysis/publication control and author COI remain unread. Existing content review remains incomplete.
- Reason for missing information: Original support/leadership roles, contracts, data/analysis/publication control and author COI remain unread.
- Required materials and conditions: Support/sponsorship, roles and independence
- Materials to obtain first: Original funding, investigator/author roles and COI
- Further research: Proposal for later research disclosing support/research roles; no new investigation, calculation or trial was performed in that production.
- Conditions for verification: Corresponding original materials and analysis scope for support/sponsorship, roles and independence should be available, with unverified matters distinguishable. Preserved wording is connected here; existing content review remains incomplete.
- Why this condition is needed: Applicability item distinguishing support/sponsorship, roles and independence and connecting materials needed for the selected question with current materials.
- Application exceptions: Limited to the stored summary for the selected formulation, population, endpoint and period. It does not substitute for numbers from other formulations/trials/endpoints or unread external material.
- Remaining uncertainty: This record links preserved-summary statements; it does not establish external-paper comparison, a new efficacy verdict or completed content review.
- Referenced methods: Chamgap's own conditions for independence and attribution. The official methodological sections used in this example do not validate every detail of these items.
- Related sources: S01

### N23 · Study mask supply and donated support

Verification status: Partly verified  
Reading scope: Summary read; external material unread

- Current findings: Original records state that study masks were supplied within the research and manufacturer donation was not verified. This is not changed to definite manufacturer supply, no support or actual receipt of 50 masks by everyone.
- Why unverified: Only corresponding preserved-summary information is recorded; detailed original materials remain unread and existing content review is incomplete. Manufacture/specifications, actual distribution, purchase/supply contracts and support scope/roles remain unverified. Existing content review remains incomplete.
- Reason for missing information: Manufacture/specifications, actual distribution, purchase/supply contracts and support scope/roles remain unverified.
- Required materials and conditions: Study supply versus manufacturer support/products and actual receipt
- Materials to obtain first: Product/distribution, purchase/supply contracts and support disclosures
- Further research: Proposal separating study supply from manufacturer support; no new investigation, calculation or trial was performed in that production.
- Conditions for verification: Corresponding original materials and analysis scope for study supply versus manufacturer support/products and actual receipt should be available, with unverified matters distinguishable. Preserved wording is connected here; existing content review remains incomplete.
- Why this condition is needed: Applicability item distinguishing study supply versus manufacturer support/products and actual receipt and connecting materials needed for the selected question with current materials.
- Application exceptions: Limited to the stored summary for the selected formulation, population, endpoint and period. It does not substitute for numbers from other formulations/trials/endpoints or unread external material.
- Remaining uncertainty: This record links preserved-summary statements; it does not establish external-paper comparison, a new efficacy verdict or completed content review.
- Referenced methods: Chamgap’s own independence/attribution conditions; the official method sections used in the pilot do not validate every detailed item; M03 §3.2.2–3.2.3; reverse-direction labels and test adaptation are independently designed; M03 §3.2.3, M08 §8.2.2–8.2.3; own application
- Related sources: S01

### N24 · Medical writing, publication costs and author relationships

Verification status: Partly verified  
Reading scope: Summary read; external material unread

- Current findings: Original records state that medical-writing/publication-cost support was not verified. Unverified is not changed to absent, and funding/leadership names do not fill all author COI.
- Why unverified: Only corresponding preserved-summary information is recorded; detailed original materials remain unread and existing content review is incomplete. Complete original writing/publication, outside analysis, author relationships/contributions and support remain unread. Existing content review remains incomplete.
- Reason for missing information: Complete original writing/publication, outside analysis, author relationships/contributions and support remain unread.
- Required materials and conditions: Unverified support items and author/analysis roles
- Materials to obtain first: Writing/publication/analysis, author-contribution and COI disclosures
- Further research: Proposal disclosing support items separately; no new investigation, calculation or trial was performed in that production.
- Conditions for verification: Corresponding original materials and analysis scope for unverified support items and author/analysis roles should be available, with unverified matters distinguishable. Preserved wording is connected here; existing content review remains incomplete.
- Why this condition is needed: Applicability item distinguishing unverified support items and author/analysis roles and connecting materials needed for the selected question with current materials.
- Application exceptions: Limited to the stored summary for the selected formulation, population, endpoint and period. It does not substitute for numbers from other formulations/trials/endpoints or unread external material.
- Remaining uncertainty: This record links preserved-summary statements; it does not establish external-paper comparison, a new efficacy verdict or completed content review.
- Referenced methods: Chamgap independence/attribution conditions. The referenced official method sections do not certify every detail of these items; Data collection/selection principles in M04 §4.5–4.6; Access/reading separation and hyperlink rules are Chamgap design
- Related sources: S01

### N25 · One trial, bibliographic years and sibling sheets

Verification status: Partly verified  
Reading scope: Summary read; external material unread

- Current findings: Preserve Bundgaard 2020 DANMASK-19 in the evidence list and 2021 publication bibliography in the citation list. These do not become separate trials/replications or new participant totals across groups/tests/events/timepoints/sibling sheets.
- Why unverified: Only corresponding preserved-summary information is recorded; detailed original materials remain unread and existing content review is incomplete. Unique clinical-trial/participant totals or independent replication of the same question are not newly established. Existing content review remains incomplete.
- Reason for missing information: Unique clinical-trial/participant totals or independent replication of the same question are not newly established.
- Required materials and conditions: Evidence-list 2020, citation-list 2021 and the same DANMASK relationship
- Materials to obtain first: Report/registration/cohort relationships and separate research materials
- Further research: Proposal for later independent comparative research on the same selected question; no new investigation, calculation or trial was performed in that production.
- Conditions for verification: Corresponding original materials and analysis scope for evidence-list 2020, citation-list 2021 and the same DANMASK relationship should be available, with unverified matters distinguishable. Preserved wording is connected here; existing content review remains incomplete.
- Why this condition is needed: Applicability item distinguishing evidence-list 2020, citation-list 2021 and the same DANMASK relationship and connecting materials needed for the selected question with current materials.
- Application exceptions: Limited to the stored summary for the selected formulation, population, endpoint and period. It does not substitute for numbers from other formulations/trials/endpoints or unread external material.
- Remaining uncertainty: This record links preserved-summary statements; it does not establish external-paper comparison, a new efficacy verdict or completed content review.
- Referenced methods: M04 §4.6.1–4.6.2 distinction between studies and reports; cohort/outcome linkage is a custom application; M04 §4.6.1–4.6.2, M15 §15.3.1; custom application; M04 §4.5, §4.6.3; limits on current material conversion reflect the review scope and custom design
- Related sources: S01

### N26 · Generalization across duration, setting and products

Verification status: Partly verified  
Reading scope: Summary read; external material unread

- Current findings: The scope is 2020 Denmark, low community mask use, a surgical-mask recommendation and one month. Effects are not extended to healthcare, other variants/epidemics, long-term use, mandates or other masks/products.
- Why unverified: Only corresponding preserved-summary information is recorded; detailed original materials remain unread and existing content review is incomplete. Direct comparisons, sustained/discontinued exposure and long-term outcomes in other situations/products remain unverified. Existing content review remains incomplete.
- Reason for missing information: Direct comparisons, sustained/discontinued exposure and long-term outcomes in other situations/products remain unverified.
- Required materials and conditions: Original recommendation/setting versus other situations and long-term effects
- Materials to obtain first: Direct setting/product/duration-specific research and follow-up
- Further research: Proposal distinguishing question/situation/duration applicability; no new investigation, calculation or trial was performed in that production.
- Conditions for verification: Corresponding original materials and analysis scope for original recommendation/setting versus other situations and long-term effects should be available, with unverified matters distinguishable. Preserved wording is connected here; existing content review remains incomplete.
- Why this condition is needed: Applicability item distinguishing original recommendation/setting versus other situations and long-term effects and connecting materials needed for the selected question with current materials.
- Application exceptions: Limited to the stored summary for the selected formulation, population, endpoint and period. It does not substitute for numbers from other formulations/trials/endpoints or unread external material.
- Remaining uncertainty: This record links preserved-summary statements; it does not establish external-paper comparison, a new efficacy verdict or completed content review.
- Referenced methods: M03 §§3.2.1–3.2.4; dose, durability and effect-modification details are Chamgap-designed; M03 §§3.2.2–3.2.3; reverse-direction labels and assessment adaptation are Chamgap-designed
- Related sources: S01

### N27 · Unknown safety and unquantified harms

Verification status: Partly verified  
Reading scope: Summary read; external material unread

- Current findings: The original parent safety is Unknown and mask-related harms were not quantified. Infection results/P are not used as evidence of no discomfort/skin irritation or of safety.
- Why unverified: Only corresponding preserved-summary information is recorded; detailed original materials remain unread and existing content review is incomplete. Adverse-event collection/types/frequency/denominators, discontinuation and long-term/vulnerable-population harms remain unverified. Existing content review remains incomplete.
- Reason for missing information: Adverse-event collection/types/frequency/denominators, discontinuation and long-term/vulnerable-population harms remain unverified.
- Required materials and conditions: Discomfort/skin irritation and harms collection/denominator/follow-up scope
- Materials to obtain first: Harms collection, adverse events/discontinuation and follow-up
- Further research: Proposal for later research specifying harms collection/scope; no new investigation, calculation or trial was performed in that production.
- Conditions for verification: Corresponding original materials and analysis scope for discomfort/skin irritation and harms collection/denominator/follow-up scope should be available, with unverified matters distinguishable. Preserved wording is connected here; existing content review remains incomplete.
- Why this condition is needed: Applicability item distinguishing discomfort/skin irritation and harms collection/denominator/follow-up scope and connecting materials needed for the selected question with current materials.
- Application exceptions: Supplement the selected subclaim’s safety-material gaps. Wearer-infection results or parent safety wording do not establish safety or create harms rates or new usage instructions.
- Remaining uncertainty: This record links preserved-summary statements; it does not establish external-paper comparison, a new efficacy verdict or completed content review.
- Referenced methods: M19 §19.1.2–19.2.4; detailed distinctions are Chamgap’s own design; M19 §19.1.2–19.2.4; Chamgap application; M19 §19.1.2–19.2.4; Chamgap application; M19 §19.1.2–19.2.4; Chamgap application
- Related sources: S01

### N28 · Original values, both languages, dates, corrections and history

Verification status: Partly verified  
Reading scope: Summary read; external material unread

- Current findings: Preserve parent D34, B/H/R1/I2/E0/B2/C0, the large hard-endpoint RCT true marker, two false markers, empty override reasons and subclaim D/note. Both languages, 2026-08-26, empty corrections/deliberation and cross-validation are not current review or a subclaim score.
- Why unverified: Only corresponding preserved-summary information is recorded; detailed original materials remain unread and existing content review is incomplete. Absent subclaim score/status/axes are not filled with parent values; no new methodological/efficacy certification. Existing content review remains incomplete.
- Reason for missing information: Absent subclaim score/status/axes are not filled with parent values; no new methodological/efficacy certification.
- Required materials and conditions: Parent/subclaim scores/axes versus historical verification/dates
- Materials to obtain first: Original corrections, versions and user correction comments
- Further research: Proposal separating original values/history from new-material application; no new investigation, calculation or trial was performed in that production.
- Conditions for verification: Corresponding original materials and analysis scope for parent/subclaim scores/axes versus historical verification/dates should be available, with unverified matters distinguishable. Preserved wording is connected here; existing content review remains incomplete.
- Why this condition is needed: Applicability item distinguishing parent/subclaim scores/axes versus historical verification/dates and connecting materials needed for the selected question with current materials.
- Application exceptions: Limited to the stored summary for the selected formulation, population, endpoint and period. It does not substitute for numbers from other formulations/trials/endpoints or unread external material.
- Remaining uncertainty: This record links preserved-summary statements; it does not establish external-paper comparison, a new efficacy verdict or completed content review.
- Referenced methods: M04 §4.5, §4.6.3; limits of this material conversion follow the review scope and internal design; M03 §3.1, §3.2.1–3.2.4 question-clarification principles; detailed separation rules are internally designed
- Related sources: S01

### N29 · Actual summary reading and material links

Verification status: Partly verified  
Reading scope: Summary read; external material unread

- Current findings: The complete preserved summary/bibliography were used for production and links retained. External paper/registration/protocol/SAP/support/COI originals remain unread/unaccessed; external link testing was not performed.
- Why unverified: Only corresponding preserved-summary information is recorded; detailed original materials remain unread and existing content review is incomplete. External original content, exact contracts/denominators/models and access availability remain unverified. Existing content review remains incomplete.
- Reason for missing information: External original content, exact contracts/denominators/models and access availability remain unverified.
- Required materials and conditions: Preserved-summary reading versus external paper/registration/plan access
- Materials to obtain first: Original paper, registration, protocol, SAP and support materials or user comments
- Further research: Proposal for updating while distinguishing actual acquisition/timing/scope; no new investigation, calculation or trial was performed in that production.
- Conditions for verification: Corresponding original materials and analysis scope for preserved-summary reading versus external paper/registration/plan access should be available, with unverified matters distinguishable. Preserved wording is connected here; existing content review remains incomplete.
- Why this condition is needed: Applicability item distinguishing preserved-summary reading versus external paper/registration/plan access and connecting materials needed for the selected question with current materials.
- Application exceptions: Limited to the stored summary for the selected formulation, population, endpoint and period. It does not substitute for numbers from other formulations/trials/endpoints or unread external material.
- Remaining uncertainty: This record links preserved-summary statements; it does not establish external-paper comparison, a new efficacy verdict or completed content review.
- Referenced methods: M04 §4.5–4.6 material collection/selection principles; acquisition/reading separation and hyperlink specifications are internally designed; M04 §4.5, §4.6.3; limits of this material conversion follow the review scope and internal design
- Related sources: S01

## Evidence and sources

### S01

Bundgaard H et al. 2020 DANMASK-19

[PubMed](https://pubmed.ncbi.nlm.nih.gov/33205991/)

Materials actually read: Summary read; external material unread  
Findings recorded in the summary: 42/2,392(1.8%) versus 53/2,470(2.1%); difference −0.3 percentage points (−1.2–0.4), P=.38; OR 0.82(0.54–1.23), P=.33  
Record level: Outcome wording in the stored summary  
Independent replication: S01 DANMASK-19 compares a surgical-mask recommendation/50 masks/instructions with concurrent public-health advice in 2020 Denmark, where community wearing was uncommon. Distinguish 6,024 allocated (3,030/2,994) from 4,862 primary complete cases (2,392/2,470), with 19.3% missingness. Self-reported wearing 46/47/7%, one-month wearer infection by antibody/PCR/hospital diagnosis, 42/2,392 versus 53/2,470, original absolute difference −0.3 percentage points/CI −1.2–0.4/P=.38 and OR 0.82/CI 0.54–1.23/P=.33 are separate exposures/endpoints/estimands. Transmission to others/mandates were unmeasured. Complete-case results are not relabeled as ITT for all, full wearing, generally zero effects or safety. Evidence-list 2020 and citation-list 2021 concern the same report identity. People/groups/tests/events/timepoints, bibliographies/registrations and sibling sheets are not summed as new independent trials/participants. Report entries are not unique clinical totals; no new calculations, independence certification or procedural guidance.

| Material | Public availability | Access status | Actually read | Notes |
|---|---|---|---|---|
| Stored summary | Stored file | Stored summary | Summary read | Only stored-summary and bibliographic content was used for production. External material verification/review is not complete. |
| External paper | Public availability unverified; only bibliography links preserved | Unread; access not attempted | Not read | No external access or click testing was performed in the original preparation. URLs or registration identifiers alone do not upgrade acquisition/reading status. |
| Registration material | Public availability unverified; only bibliography links preserved | Unread; access not attempted | Not read | No external access or click testing was performed in the original preparation. URLs or registration identifiers alone do not upgrade acquisition/reading status. |
| Protocol | Public availability unverified; only bibliography links preserved | Unread; access not attempted | Not read | No external access or click testing was performed in the original preparation. URLs or registration identifiers alone do not upgrade acquisition/reading status. |
| Statistical analysis plan | Public availability unverified; only bibliography links preserved | Unread; access not attempted | Not read | No external access or click testing was performed in the original preparation. URLs or registration identifiers alone do not upgrade acquisition/reading status. |
| Funding, product-support and COI material | Public availability unverified; only bibliography links preserved | Unread; access not attempted | Not read | No external access or click testing was performed in the original preparation. URLs or registration identifiers alone do not upgrade acquisition/reading status. |

## Review criteria and methods

These are Chamgap's own application conditions, informed by the relevant sections of official methodological guidance. They do not constitute official assessment-tool certification or a new efficacy score.

- M03 [Cochrane Handbook 6.5 (2024), chapter updated 2023-08](https://www.cochrane.org/authors/handbooks-and-manuals/handbook/current/chapter-03) · §3.1, §3.2.1–3.2.3, MECIR C5/C7/C13 · Clearly record the question, eligibility conditions and reasons for changes, and distinguish variations in interventions. · Preserved method HTML copies; no current method-content re-review or official tool execution
- M04 [Cochrane Handbook 6.5.1 (2025), chapter updated 2025-03](https://www.cochrane.org/authors/handbooks-and-manuals/handbook/current/chapter-04) · §4.5, §4.6.1–4.6.3, MECIR C42 · Distinguish studies from reports and link them; do not omit a study solely because results are unreported. · Preserved method HTML copies; no current method-content re-review or official tool execution
- M08 [Cochrane Handbook 6.5 (2024), chapter updated 2019-10](https://www.cochrane.org/authors/handbooks-and-manuals/handbook/current/chapter-08) · §8.1–8.2.3, Table 8.2.a · Define the outcome and effect of interest, then examine randomization, deviations, missing data, measurement and selective reporting. · Preserved method HTML copies; no current method-content re-review or official tool execution
- M15 [Cochrane Handbook 6.5 (2024), chapter updated 2023-08](https://www.cochrane.org/authors/handbooks-and-manuals/handbook/current/chapter-15) · §15.2.4, §15.3.1–15.3.3 · Distinguish effect estimates, intervals, importance and applicability. Sample size alone does not determine precision. · Preserved method HTML copies; no current method-content re-review or official tool execution
- M19 [Cochrane Handbook 6.5 (2024), chapter updated 2019-10](https://www.cochrane.org/authors/handbooks-and-manuals/handbook/current/chapter-19) · §19.1.2, §19.2.1–19.2.4 · Harm questions may require different designs, populations and follow-up from efficacy questions. Case reports do not establish incidence rates. · Preserved method HTML copies; no current method-content re-review or official tool execution

## What the statuses mean

- Met: Status for necessary evidence confirmed after existing content review. No completion is declared in the current presentation.
- Partly verified: Some information in the stored summary is linked into the table. External comparison/content review is not complete.
- Unverified: The article leaves this unverified, or required material is absent from the current stored summary. This is distinct from zero, absence or safety.
- Review incomplete: Existing content review remains incomplete.
- Not reported: Not reported within the stored material actually read; not extended to the entire primary paper.
- Inaccessible: Means an actual access failure. Access not attempted here is not assigned this state.
- Not applicable: Not used as a substitute for an evidence gap.
- Conflicting data: Requires an observed disagreement under the same comparison criteria; not automatically judged in this production.
- Insufficient evidence for the conditions: Marks a gap in additional material required by the selected conditions; not a new efficacy grade.

## Change history

2026-10-14 · Public page/materials 1.0. Public pages and materials were created from the existing 29 items. No new clinical search, verification-status change or scoring was performed.