- Design
- Systematic review of 75 studies (12 RCTs, 49 observational)
- Population
- Older adults, pregnant women and infants receiving US-licensed RSV vaccines or antibodies
- Primary outcome
- Effectiveness against RSV hospitalisation; safety
- Effect
- Older adults VE 83.3% (95% CI 42.9–96.9%); nirsevimab 63.6–93.0%; maternal 51–70%
A companion systematic review for the 2026–27 season included 75 studies of US-licensed RSV vaccines and monoclonal antibodies: 12 randomised trials and 49 observational studies.
In adults 60 and over, RSV vaccination was associated with 83% lower RSV hospitalisation (95% CI 43–97%). One study found effectiveness significantly lower at 12–18 months than in the first season; another found no significant difference between one and two seasons. Maternal vaccination at 32–36 weeks was associated with 51–70% lower infant RSV hospitalisation. Nirsevimab effectiveness in infants ranged from 64% to 93% depending on timing.
There were no Guillain-Barré cases in three trials, but one self-controlled case series in older adults found a possible raised risk in the 42 days after vaccination. No comparative study linked maternal vaccination to preterm birth. The practical change is twofold: older adults who were vaccinated last season should not assume they are still fully protected, and infants should be covered either by maternal vaccination or nirsevimab.
- Recommend RSV vaccination to adults 75 and over and to 60–74-year-olds with heart, lung, kidney disease, diabetes or frailty.
- Do not assume a dose given last season still protects fully — waning was seen in one study; follow national guidance on revaccination.
- Make sure every infant entering their first RSV season is covered by maternal vaccination at 32–36 weeks or by nirsevimab.
- Mention the possible Guillain-Barré signal when consenting older adults; it is rare and not confirmed.
- Check local availability and cost; RSV products are not yet widely available in Indian public programmes.
Why it matters
Waning after the first season changes the assumption that a single RSV vaccine dose protects for years.
Don't overread it
The waning signal comes from one study and was not confirmed in another; it is not yet grounds for routine revaccination.
The statistics, in plain English
83% effectiveness sounds precise, but the confidence interval (43–97%) is wide — protection is clearly substantial, its exact size is not. A maternal VE interval running from −30% to 83% in one study means that study alone could not show protection.
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