COVID and RSV shots still cut severe illness, two 2026-2027 season reviews find

Ahead of the 2026-2027 respiratory season, JAMA published two systematic reviews on 2 September summarising the latest evidence on the vaccines meant to blunt it — one for COVID-19, one for respiratory syncytial virus (RSV) [s1][s2]. Their combined message is unshowy but policy-relevant: the shots still reduce severe illness across age groups, no new safety alarms surfaced, and protection fades over time in ways that shape when people should get them.

What the reviews covered

Both were structured evidence syntheses searching the major databases through 29 June 2026. The COVID-19 review screened 11,829 references and included 155 publications — 15 randomised trials, 84 comparative observational studies, 38 single-group safety studies and 18 descriptive burden studies [s1]. The RSV review included 75 studies, among them 12 randomised trials [s2]. These are the kind of comprehensive appraisals that feed formal immunisation recommendations rather than one-off trial headlines.

COVID-19: steady protection against severe disease

For COVID-19, updated vaccines were again associated with a lower risk of hospitalisation. Among adults 65 and older, vaccine effectiveness against hospitalisation was 53.0% (95% CI, 37.0% to 65.0%) for the 2025-2026 season; among adults 18 to 64, it was 54.0% (95% CI, 1.0% to 78.0%) for 2024-2025 [s1]. The near-identical point estimates but very different interval widths — the younger-adult estimate barely clears zero at its lower bound — are a reminder that a headline percentage can rest on far shakier data than it appears.

The reviews are most striking on the very young and the pregnant. Maternal vaccination was associated with a 58.0% (95% CI, 24.0% to 77.0%) reduction in COVID-related emergency or urgent-care visits for the mother, and with 50.0% to 54.0% fewer COVID-related hospital contacts in the first two months of life among infants born afterward, regardless of the trimester of vaccination [s1]. In children aged nine months to four years, vaccination was associated with a 76.0% (95% CI, 58.0% to 87.0%) reduction in COVID-related emergency visits [s1]. Immunocompromised adults saw a reduction in critical illness with effectiveness ranging from 32.0% to 53.0% [s1].

On safety, the review reported no new signals. Adverse events of special interest — stroke, thrombosis, myocarditis and others — were consistent with prior reviews, and no study conducted under the updated guidance on extended dosing intervals reported increased myocarditis or pericarditis [s1].

RSV: strong early protection that appears to wane

The RSV review points in the same broad direction with an important caveat about durability. In older adults, RSV vaccination was associated with an 83.3% (95% CI, 42.9% to 96.9%) reduction in RSV-related hospitalisation [s2]. But the evidence suggests that protection may be lower in subsequent seasons than in the first — one study found higher effectiveness in the first season than at 12 to 18 months, though another found no significant drop between one and two seasons [s2].

For infants, two tools were assessed. Maternal vaccination between 32 and 36 weeks' gestation showed effectiveness against infant RSV hospitalisation ranging from 51.0% (95% CI, −29.6% to 83.3%) to 70.0% (95% CI, 37.0% to 86.0%) [s2]. The monoclonal antibody nirsevimab showed effectiveness ranging from 63.6% (95% CI, 26.9% to 81.9%) to 93.0% (95% CI, 83.0% to 97.0%) against RSV hospitalisation within six to twelve months, varying by timing [s2].

The RSV safety findings were reassuring with one flagged uncertainty. No cases of Guillain-Barré syndrome occurred across three randomised trials, though one self-controlled case series reported a possible increased risk in the 42 days after vaccination in older adults [s2]. None of the comparative studies found an association between RSV vaccination in pregnancy and preterm birth or other adverse pregnancy outcomes [s2].

Why it matters for the season ahead

These are the evidence documents that sit under vaccine policy, and their value is in the aggregate picture rather than any single number: across dozens of trials and observational studies, both vaccine programmes were consistently associated with less severe disease, and neither review surfaced a new safety concern [s1][s2]. That is the substantive news in a period when vaccine recommendations have been unusually contested.

The findings also carry limits worth stating. Effectiveness estimates are mostly against severe outcomes like hospitalisation, not infection; many rest on observational data; and the RSV signal on waning protection means timing matters, not just uptake [s1][s2]. This article summarises evidence and is not medical advice; decisions about specific vaccines belong with a clinician. What the paired reviews establish is that, going into 2026-2027, the case for these vaccines against severe respiratory illness still holds on the evidence.