RS-virus hospitalisations among infants drop sharply after maternal vaccine

Hospitalisations of infants under six months for RS-virus have fallen by 78% since Denmark introduced a maternal vaccine last autumn, the Statens Serum Institut (SSI) reports.

For newborns aged three months or younger, admissions linked to the virus have dropped by over 70% compared with the previous year.

Bolette Søborg, section head and senior physician at SSI, said the sharp reduction reflects both high vaccine effectiveness and strong uptake among pregnant women.

The vaccine, offered free to pregnant women, transfers antibodies to the unborn child. Before its introduction, Denmark averaged 1,300 annual hospitalisations of infants under one year with RS-virus, according to the Danish Health Authority.

SSI’s figures are based on data from 22,593 children born between November 2025 and March 2026.