# MATISSE trial (maternal RSV vaccine, infant outcomes)

Study · id `maternal:matisse-trial` · Maternal & Newborn Atlas · release `c7fb95f1d15a7d13` (public)

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Also called: MATISSE; C3671008

Browse, life stage: Pregnancy; Infant follow-up  
Browse, care area: The baby's first year  

## In plain language

A large international trial of an RSV vaccine given to pregnant women, with illness in their babies as the main outcome. Women were randomly given the vaccine or a placebo (a dummy injection). The vaccine lowered severe RSV lung illness in babies; for RSV illness of any severity at 90 days the results did not meet the trial's statistical success criterion.

## Technical summary

Registry NCT04424316, lead sponsor Pfizer (sponsor class industry), phase 3, interventional, randomised, parallel, quadruple masking, prevention; COMPLETED. The registry enrolment of 14727 counts mothers and infants together (its participant flow says 7420 maternal participants and 7307 infant participants); the paper's counts (3682 and 3676 maternal participants who received vaccine or placebo, and 3570 and 3558 infants evaluated) are recorded with their own units. The trial paper (2023) was read as a PubMed abstract only. The abstract reports an interim analysis in which one of two primary end points met the success criterion.

## Key facts

- Design: Phase 3, randomised, double-blind, placebo-controlled trial in pregnant women, with the outcomes counted in their infants. Registry values: allocation randomized, intervention model parallel, masking quadruple, primary purpose prevention. Women at 24 through 36 weeks' gestation were randomised 1:1 to one injection of RSVpreF or placebo (PubMed abstract).
- Phase: Phase 3
- Enrolled: 14727 participants, maternal and infant together (participant flow: 7420 maternal and 7307 infant participants) (enrolled count; A Trial to Evaluate the Efficacy and Safety of RSVpreF in Infants Born to Women Vaccinated During Pregnancy., snapshot `maternal:ctgov-nct04424316-2026-10-15`, retrieved 2026-10-15); 3682 maternal participants who received vaccine (paper abstract) (treated count; Bivalent Prefusion F Vaccine in Pregnancy to Prevent RSV Illness in Infants, snapshot `maternal:pubmed-37018474-2026-10-15`, retrieved 2026-10-15); 3676 maternal participants who received placebo (paper abstract) (treated count; Bivalent Prefusion F Vaccine in Pregnancy to Prevent RSV Illness in Infants, snapshot `maternal:pubmed-37018474-2026-10-15`, retrieved 2026-10-15); 3570 infants of vaccinated women who were evaluated (paper abstract) (unknown count; Bivalent Prefusion F Vaccine in Pregnancy to Prevent RSV Illness in Infants, snapshot `maternal:pubmed-37018474-2026-10-15`, retrieved 2026-10-15); 3558 infants of placebo recipients who were evaluated (paper abstract) (unknown count; Bivalent Prefusion F Vaccine in Pregnancy to Prevent RSV Illness in Infants, snapshot `maternal:pubmed-37018474-2026-10-15`, retrieved 2026-10-15)
- Started: 2020-06-17 (actual) (A Trial to Evaluate the Efficacy and Safety of RSVpreF in Infants Born to Women Vaccinated During Pregnancy., snapshot `maternal:ctgov-nct04424316-2026-10-15`, retrieved 2026-10-15)
- Primary completion: 2023-10-27 (actual) (A Trial to Evaluate the Efficacy and Safety of RSVpreF in Infants Born to Women Vaccinated During Pregnancy., snapshot `maternal:ctgov-nct04424316-2026-10-15`, retrieved 2026-10-15)
- Completion: 2023-10-27 (actual) (A Trial to Evaluate the Efficacy and Safety of RSVpreF in Infants Born to Women Vaccinated During Pregnancy., snapshot `maternal:ctgov-nct04424316-2026-10-15`, retrieved 2026-10-15)
- Results first posted: 2025-02-11 (actual) (A Trial to Evaluate the Efficacy and Safety of RSVpreF in Infants Born to Women Vaccinated During Pregnancy., snapshot `maternal:ctgov-nct04424316-2026-10-15`, retrieved 2026-10-15)
- Countries: United States; Argentina; Australia; Brazil; Canada; Chile; Denmark; Finland; Japan; Mexico; Netherlands; New Zealand; Philippines; South Africa; South Korea; Spain; Taiwan; Gambia (A Trial to Evaluate the Efficacy and Safety of RSVpreF in Infants Born to Women Vaccinated During Pregnancy., snapshot `maternal:ctgov-nct04424316-2026-10-15`, retrieved 2026-10-15)
- Care setting: Pregnant women recruited at sites in 18 countries; the abstract gives no further detail of the care setting. (Bivalent Prefusion F Vaccine in Pregnancy to Prevent RSV Illness in Infants, snapshot `maternal:pubmed-37018474-2026-10-15`, retrieved 2026-10-15)
- Registry status: "COMPLETED" (U.S. National Library of Medicine (ClinicalTrials.gov), snapshot `maternal:ctgov-nct04424316-2026-10-15`, retrieved 2026-10-15)

## Connected pages

- Tests RSV vaccination in pregnancy for infant outcomes: RSV vaccination in pregnancy to protect the infant (`maternal:maternal-rsv-vaccination`)
- The vaccine substance tested: RSVpreF (bivalent RSV prefusion F protein vaccine) (`maternal:rsvpref-vaccine`)

## Provenance

Content hash: e6bb7b0a6f0e9d8e9c18d266b9de5c8637c1edb585708ec67bd424abfe24c13d
Last substantive edit: 2026-10-15
Evidence last checked: 2026-10-15