Respiratory syncytial virus (RSV) vaccine !
Prefusion F protein vaccine. Given in late pregnancy, the mother's antibodies cross the placenta and protect the baby in its first months.
Updated 2026-11-01
Also called: Maternal RSV vaccine, RSVpreF, VSR (Spanish)
The figure shows RSV F stabilised in its prefusion shape by a human antibody; vaccines use stabilised prefusion F because it carries the most potent neutralising sites.
Mechanism of action
RSV F protein fuses the virus with airway cells. Its prefusion shape displays the sites most targeted by neutralising antibodies, so vaccines use F locked in that shape. In maternal vaccination, the mother's IgG crosses the placenta and protects the newborn during the months of highest risk; this protection wanes over time.
- Stabilised prefusion F protein is injected in late pregnancy
- The mother makes neutralising IgG against F
- IgG crosses the placenta to the fetus
- The newborn is protected against severe RSV in its first months
Pharmacokinetics
- Distribution
- Maternal IgG crosses the placenta; the infant's protection wanes over the first months
Indications
- Colombian PAI since November 2025: all pregnant women from week 28 to week 36 of gestation, to protect the infant (MinSalud)
- Prevention of severe RSV lower respiratory tract disease (bronchiolitis, pneumonia) in young infants
Adverse effects
Common
- Local reactions at the injection site
Contraindications
- Severe allergic reaction to a component
Key interactions
- Nirsevimab (infant monoclonal antibody)
- Alternative ways to protect the infant: most babies do not need both
What is monitored
- Gestational age at vaccination, recorded on the prenatal card
- Infant's maternal vaccination status, to decide on nirsevimab
Administration and safety
- Intramuscular route
- Check gestational age: the vaccine is given only within the window set by the national programme
- Do not confuse the maternal RSV vaccine with infant monoclonal antibodies
- Record it on the prenatal card so the newborn's team knows
Nursing care
- Confirm the weeks of gestation before vaccinating
- Record the vaccination for the baby's team
- Explain that protection passes to the baby and fades over the first months
Pregnancy and breastfeeding
Designed to be given in pregnancy, within the gestational window set by the national programme, to protect the infant.
Test yourself
Think of the answer, then tap the question to see it.
Why do RSV vaccines use the prefusion form of F?
Prefusion F carries the most potent neutralising antibody sites.
How does maternal RSV vaccination protect the newborn?
The mother's IgG against F crosses the placenta and gives the infant passive protection in its first months.
Does an infant whose mother received the RSV vaccine usually also need nirsevimab?
Most do not need both; nirsevimab is used when the mother was not vaccinated in time.
Related drugs
← Back to the class: Viral vaccines
Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.
Sources: Lineamiento Técnico y Operativo de la Primera Jornada Nacional de Vacunación (Ministerio de Salud y Protección Social (Colombia), 2026); RSV Vaccine Guidance for Pregnant Women (Centers for Disease Control and Prevention, 2025); ATCDDD - ATC/DDD Index (WHO Collaborating Centre for Drug Statistics Methodology, 2026).
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Representative model, for educational purposes only.