RSV Vaccines & Antibodies
After a harmful 1960s failure, stabilised-protein vaccines (May 2023) and the antibody nirsevimab now protect older adults and infants against RSV.
Open in the interactive tree →A formalin-inactivated RSV vaccine tested in the 1960s worsened disease, with about 80% of vaccinated children hospitalised versus 5% of controls and two deaths, and it stalled the field for decades. A 2013 crystal-structure study of the fusion (F) protein showed how to stabilise its pre-fusion form, which led to the first approvals: GSK's Arexvy (3 May 2023) and Pfizer's Abrysvo (31 May 2023), the latter also for pregnant women at 32-36 weeks to protect newborns, followed by Moderna's mRNA vaccine Mresvia (May 2024). The single-dose antibody nirsevimab was approved in the EU in November 2022 and in the US in July 2023.
As of October 2026
US surveillance found RSV hospitalisations among infants aged 0-7 months in 2024-25 were 28% to 43% lower than in 2018-20, and 45% to 52% lower among infants aged 0-2 months (MMWR, summarised by CIDRAP). A May 2025 Lancet Child & Adolescent Health meta-analysis of 27 studies from France, Italy, Luxembourg, Spain and the US found an 83% reduction in the odds of RSV hospitalisation with nirsevimab in infants under 12 months. At participating US health systems in the 2023-24 season 71.7% of infants were immunised, 31.9% through maternal vaccination and 42.5% with nirsevimab.
Open steps
- When to revaccinate older adults Medium AI leverageIn 131,379 adults over 60, vaccine effectiveness against RSV hospitalisation was 83% in season one and 56% in season two, with a wide interval. When is a booster needed?
- Antibody-resistant RSV variants Medium AI leverageRSV-B viruses with the F:N201T change, which nirsevimab recognises less well, caused hospitalised breakthrough cases in Spain in 2025/26. Will escape spread, and what replaces it?
- Rare safety signals after licensing Medium AI leverageInfant trials of two mRNA RSV vaccines showed more severe RSV in vaccinees, and older-adult labels carry a Guillain-Barre warning. Are these signals real, and how large?
- Combined and next-virus vaccines Medium AI leverageA phase 3 of an RSV plus hMPV vaccine in about 30,000 adults over 60 is under way. Can the pre-fusion design recipe be carried to hMPV, parainfluenza and flu?
Where AI could help
Medium AI leverage. Computer-designed antigens already helped shape RSV vaccines; further gains need trials in new age groups and for related viruses.
- Design stabilised antigens for related viruses such as hMPV
- Predict which mutations let the virus escape antibodies
- Design longer-acting antibodies against the pre-fusion F protein
- Model who benefits most to target immunisation campaigns
Shown so far
- In March 2019 the University of Washington's Institute for Protein Design reported a computer-designed nanoparticle carrying stabilised RSV F protein that was ten times more potent than the same protein alone. source
Prerequisites
- Vaccination1796
- Genetic engineering1973Modern RSV vaccines are recombinant prefusion F proteins from genetic engineering
- Monoclonal antibodies1975The RSV antibody drugs are monoclonal antibodies
- mRNA technology2020