Giving every newborn a long-acting monoclonal antibody against respiratory syncytial virus (RSV) at birth could prevent about 61% of RSV hospital admissions among infants aged zero to two months if 90% of babies received it, while vaccinating pregnant women at the same coverage would prevent about 52%, according to a multi-model assessment published October 28 by the European Centre for Disease Prevention and Control (ECDC). The analysis pooled 10 independent models across 28 EU/EEA countries and is intended to feed national decisions on whether and how to introduce universal infant RSV programs ahead of the winter season.
RSV-related hospitalizations account for between 7% and 52% of all pediatric respiratory admissions depending on the country, or roughly 250,000 admissions a year across the EU/EEA, with newborns facing the highest per-capita rate, ECDC says in the assessment. Three products now allow protection of all infants rather than only those at high risk: the long-acting antibody nirsevimab (Beyfortus, AstraZeneca/Sanofi), authorized in the EU in October 2022; a second antibody, clesrovimab (Enflonsia, MSD), approved by the European Commission in June 2026; and the maternal vaccine Abrysvo (Pfizer), authorized in June 2023 for use between 24 and 36 weeks of pregnancy.
The modeling was run through RespiCompass, the European respiratory disease scenario hub that ECDC launched in 2024. Teams submitted 11 models, of which one was excluded for producing counter-intuitive outputs; the remaining three static, five dynamic transmission and two agent-based models were calibrated to a common synthetic baseline of weekly RSV admissions and run under four scenarios: antibodies or maternal vaccination, each at 90% or 20% coverage, for babies born between September 1 and March 31. Teams were asked to assume effectiveness against hospitalization of 87% for the antibodies and 71.3% for maternal vaccination, based on published studies.
At high coverage, the average reduction in admissions among zero-to-two-month-olds was 61% for antibodies, with individual model means ranging from 38% to 85%, and 52% for maternal vaccination, ranging from 29% to 73%. At 20% coverage the figures fell to 14% and 12%. Around 80% of all averted admissions occurred in the first two months of life and a further 15% at three to five months, reflecting the newborn-only design with no catch-up for older infants. On average, 37 newborns would need to receive the antibody to prevent one hospitalization, compared with 44 pregnancies for maternal vaccination, though ECDC cautions that the antibodies’ list price per dose is “substantially higher” than the vaccine’s and that the number-needed-to-immunize measure ignores cost.
“Universal immunisation of newborns against RSV can reduce the risk of hospitalisation due to respiratory infections in young children by more than half,” said Bruno Ciancio, an ECDC head of unit, in the agency’s news release. “Protecting infants from RSV in the first months of their life is particularly important.”
Why it matters
Several EU/EEA countries are deciding whether to add infant RSV protection to national programs, and the choice between an antibody given to the baby and a vaccine given to the mother has been hard to make on country-specific data, which ECDC describes as scarce and poorly comparable across borders. The assessment offers a common evidence base: both strategies cut admissions substantially, the antibody does slightly better per dose under the stated assumptions, and impact scales almost linearly with coverage, so a program’s success depends more on uptake than on which product is chosen.
ECDC says the projections are broadly consistent with early real-world results from Spain, Luxembourg, France and Italy, where nirsevimab rollouts were followed by falls in infant RSV admissions, and with published numbers needed to immunize of 41 in Quebec and Spain and 43 to 49 in England. The agency also notes that substantial hospital burden remains in infants aged three to 12 months, suggesting that catch-up immunization of babies born outside the winter window could add to the benefit.
The caveats
The baseline data are synthetic, built from published country- and age-specific hospitalization rates and a reference seasonal curve rather than observed 2025/26 admissions, and a common season shape was assumed for every country. The antibody’s edge partly reflects the higher effectiveness assumed for it; ECDC cites a French study finding no significant difference when the maternal vaccine was given at least eight weeks before delivery. Each strategy was modeled in isolation, dynamic models projected smaller gains than static ones, and the economic analysis stops at doses per admission averted, leaving product prices, delivery costs and the cost of illness to national cost-effectiveness studies. The report is an ECDC assessment, not a peer-reviewed paper.
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