RSV vaccines and antibodies cut infant hospitalizations in Denmark

RSV vaccines and monoclonal antibody injections are cutting hospitalizations for the respiratory syncytial virus, according to data reported by Nature on 12 November 2026.

Denmark's nationwide program

On 1 October 2025, Denmark introduced a nationwide policy of vaccinating pregnant people against RSV. The virus is a respiratory pathogen that usually causes mild symptoms but can lead to severe disease and even death in vulnerable people, including infants and older adults. Maternal antibodies induced by the vaccine cross the placenta to protect babies for around the first 6 months of their lives, when they are most at risk. Newborns at high risk of severe disease, including premature infants, whose mothers had not been vaccinated, were given injections of monoclonal antibodies.

Epidemiologist Caroline Klint Johannesen, a vaccine researcher at Nordsjællands Hospital in Hilleroed, Denmark, found that infant hospital admissions plummeted after the program began. She recalled a colleague remarking while analysing Danish health records for last winter: "Something’s wrong with the data. There are too few people in hospitals" with respiratory syncytial virus (RSV). Johannesen said the immunizations are working.

Global impact and risk groups

The World Health Organization (WHO) estimates that every year, RSV hospitalizes roughly 3.6 million and kills about 100,000 children under 5 years old. Of these deaths, 97% occur in low- and middle-income countries (LMICs).

The virus is also dangerous to older adults, although those risks are widely underappreciated by both physicians and the public. Historically, testing has been sparse, and there are no global statistics for RSV-related adult deaths. But over the age of 60, hospitalizations and mortality increase with age, especially in people with other diseases such as chronic heart and lung conditions. In the United States, the Centers for Disease Control and Prevention (CDC) estimates that between around 10,000 and 25,000 people have died in each of the past two winters, especially in older age groups.

Available immunizations

Since 2022, when European regulators approved nirsevimab — a long-acting monoclonal antibody against RSV — a second antibody and three vaccines have been developed for use in adults, one of which is suitable for pregnant people. Dozens of countries across Europe, Asia and North and South America have launched various immunization programmes.

Buddy Creech, a paediatrician at Vanderbilt University in Nashville, Tennessee, said: "It’s just remarkable" to have gone "from no mechanism to prevent RSV to an embarrassment of riches".

Why it matters

Protection against RSV must expand to lower-income countries, which are harder hit. The data from Denmark show that maternal vaccination and monoclonal antibody treatments can sharply reduce infant hospitalizations, offering a model for other countries considering similar programmes.

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Sources

• nature.com: RSV vaccines slash infections: data show jabs’ staggering success against dangerous virus | Nature

This article was drafted with AI assistance and checked against the sources above. Company claims are reported as claims. Cover image is AI-generated.