Verdict No. 2352 · Search date 2026-08-07 · Methodology v0.7
Inactivated influenza vaccination during pregnancy,
does it really help with Prevention of laboratory-confirmed influenza in infants through six months?
30-Second Summary
A
Evidence Grade A · 86 · Safety acceptable
Vaccination during pregnancy reduces laboratory-confirmed influenza in infants through six months.
Common effects are injection-site pain and transient systemic symptoms; randomized trials did not identify a serious vaccine-related safety signal.
What the
research showsA. In saline-placebo trials, laboratory-confirmed infant influenza was 19/1,026 versus 37/1,023 in South Africa and 74/1,820 versus 105/1,793 in Nepal. The publication author lists did not overlap.
research showsA. In saline-placebo trials, laboratory-confirmed infant influenza was 19/1,026 versus 37/1,023 in South Africa and 74/1,820 versus 105/1,793 in Nepal. The publication author lists did not overlap.
What the
ads claimThe evidence should not be expanded to prevention of every cold or respiratory symptom.
ads claimThe evidence should not be expanded to prevention of every cold or respiratory symptom.
Useful facts when choosing a product
- Madhi and Steinhoff both used saline placebo and had zero overlapping authors.
- Zaman used pneumococcal vaccine and Tapia used meningococcal conjugate vaccine, so neither forms the direct placebo-controlled replication pair.
- Zaman listed Gates Foundation, USAID, US HHS, National Vaccine Program Office, Wyeth, Thrasher Research Fund, Aventis Pasteur, ICDDR,B, and Johns Hopkins Bloomberg School of Public Health support.
- Madhi listed Gates Foundation, NIH/NCATS Colorado CTSI, South African Research Chairs Initiative, and a Medical Research Council unit, and the study team purchased vaccine.
- Sanofi Pasteur supplied vaccine for Tapia; vaccine-supply status could not be confirmed for Zaman or Steinhoff.
- Verdict 1571 is B with 77 points for a manufacturer-sponsored single pivotal trial of maternal RSV vaccine and severe infant RSV lower respiratory illness; this verdict has independent placebo-controlled influenza trials.
Gap Measurement · Verdict 2352 · A 86
What the research actually shows
Madhi randomized 2,116 HIV-uninfected pregnant women in South Africa, and Steinhoff randomized 3,693 pregnant women in Nepal; both used saline placebo and followed infant laboratory-confirmed influenza through about six months. Their complete publication author lists had zero overlap. Active-control trials reported 6/159 versus 16/157 in Bangladesh and 52/2,064 versus 77/2,041 in Mali. The South African team purchased vaccine; Sanofi Pasteur supplied vaccine in Mali; supply status could not be confirmed for Bangladesh or Nepal.
Why this is classified as A (86)
Repeated randomized hard-endpoint protection with nonoverlapping teams supports A with 86 points; mixed funding is not manufacturer-only evidence.
Counterpoint. Protection was not demonstrated in HIV-exposed infants in the South African trial.
Rejudgment record. New verdict — Multiple randomized trials by nonoverlapping teams reproduced protection against laboratory-confirmed infant influenza through 24 weeks
Scoring profile behind this grade
| Endpoint | H | Hard endpoint - actual events such as death |
| Replication | R2 | Independently replicated across trials |
| Independence | I1 | Mixed funding sources |
| Effect size | E+ | Meets the clinically important threshold |
The scoring table and the verdict agree (A).
Sub-claim grades by effect
This ingredient is marketed for several effects. A single overall grade blends strong and weak claims together, so each effect is graded separately here. The overall grade reflects the strongest disconfirming or core claim.
| Effect (sub-claim) | Grade | Basis |
|---|---|---|
| Prevention of confirmed infant influenza | A | Positive in multiple RCTs through 24 weeks |
Cross-check — Codex and Claude
This verdict was drafted by Codex through literature review and source-existence checks, cross-checked through blind grading and adversarial audit, and settled by reapplying the methodology boundary rules. Cases with split grades were resolved through rejudgment.
Evidence Table
| Study | Design | Sample | Funding | Endpoint | Result | Weight |
|---|---|---|---|---|---|---|
| Zaman et al. 2008 | Blinded randomized active-controlled trial | 157 | Gates Foundation, USAID, US HHS, National Vaccine Program Office, Wyeth, Thrasher, Aventis Pasteur, ICDDR,B, and Johns Hopkins | First laboratory-confirmed influenza through 24 weeks | 6/159 versus 16/157; efficacy 63% (95% CI 5–85) | Pivotal RCT |
| Madhi et al. 2014 | Double-blind saline-placebo RCT | 2,116 | Gates Foundation and public research grants; vaccine purchased by the study team | Infant RT-PCR-confirmed influenza through 24 weeks | 1.9% versus 3.6%; efficacy 48.8% (11.6–70.4) | South African RCT in the direct replication pair |
| Tapia et al. 2016 | Observer-blind active-controlled randomized trial | 4,105 | Bill & Melinda Gates Foundation; vaccines supplied by Sanofi Pasteur | First laboratory-confirmed influenza through six months | 52/2,064 versus 77/2,041; efficacy 33.1% (95% CI 3.7–53.9) | Supporting RCT with a different vaccine control |
| Steinhoff et al. 2017 | Saline-placebo randomized trial | 3,693 | Bill & Melinda Gates Foundation; manufacturer vaccine-supply status could not be confirmed | Laboratory-confirmed infant influenza through six months | 74/1,820 versus 105/1,793; efficacy 30% (95% CI 5–48) | Direct replication of the South African trial with zero overlapping authors |
Receipt — 4 References
All 4 cited sources were verified for existence at the original page (as of 2026-08-07).
Zaman K, Roy E, Arifeen SE, et al. Effectiveness of Maternal Influenza Immunization in Mothers and Infants. N Engl J Med. 2008;359:1555-1564. DOI: 10.1056/NEJMoa0708630.
checkedMadhi SA, Cutland CL, Kuwanda L, et al. Influenza Vaccination of Pregnant Women and Protection of Their Infants. N Engl J Med. 2014;371:918-931. DOI: 10.1056/NEJMoa1401480.
checkedTapia MD, Sow SO, Tamboura B, et al. Maternal immunisation with trivalent inactivated influenza vaccine for prevention of influenza in infants in Mali: a prospective, active-controlled, observer-blind, randomised phase 4 trial. Lancet Infect Dis. 2016;16(9):1026-1035. DOI: 10.1016/S1473-3099(16)30054-8.
checkedSteinhoff MC, Katz J, Englund JA, et al. Year-round influenza immunisation during pregnancy in Nepal: a phase 4, randomised, placebo-controlled trial. Lancet Infect Dis. 2017;17(9):981-989. DOI: 10.1016/S1473-3099(17)30252-9.
checkedDraft and rewrite: Codex (AI) · Verification: Codex blind grading and adversarial audit · Final adjudication: Claude
Reviewed and approved: Chamgap Editorial Team · Approval date: 2026-08-07 · Corrections: none
Reviewed and approved: Chamgap Editorial Team · Approval date: 2026-08-07 · Corrections: none
Cite this verdict
[Chamgap] Maternal influenza vaccination × laboratory-confirmed infant influenza — Evidence Grade A·86. 4 cited sources checked. Source: https://chamgap.com/en/verdicts/immunity/maternal-influenza-vaccine-infant-confirmed-influenza/ · CC BY 4.0CC BY 4.0 — free to use with attribution; do not distort grades, numbers, or verdict meaning.
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