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General immunization against respiratory syncytial virus (RSV) began in Iceland in autumn 2025, and the results during the first winter have been very positive. Parental uptake was excellent, and preliminary findings indicate a substantial reduction in severe RSV infections among the youngest children. The Minister of Health has now decided to secure permanent funding for this preventive measure, and preparations are under way for a continued program.

RSV is a common cause of respiratory infections in young children and can lead to serious illness, particularly during the first months of life. To prevent such illness, infants in Iceland were offered a long-acting monoclonal antibody, nirsevimab (Beyfortus), for the first time last winter. It is administered as a single injection and provides protection for at least five to six months.

How was the program organized?

When the decision was made in spring 2025 to introduce this immunization program, it was initially established as a temporary initiative covering two winters (RSV seasons), 2025–2026 and 2026–2027. During the planning phase, the target population had to be defined and the quantity of antibody to be purchased for both seasons determined.

The decision was made to prioritize the youngest infants, as the risk of severe RSV infection is highest during the first months of life. The age criteria were based, among other things, on Icelandic data on RSV-related hospital admissions and the international research available at the time.

Under the current arrangements, the antibody is offered to infants born during the defined RSV season, from October to March, and to infants born outside that period who are younger than six months at the start of the season. For the 2026–2027 winter, this applies to infants born on or after 1 May 2026, as was also the case last year. The antibody is also offered to certain children in high-risk groups during their second year of life.

These age criteria therefore reflect the prioritization adopted when the program was launched; they do not mean that the antibody is beneficial only for infants younger than six months. The risk of severe illness generally decreases with age, but there is no sharp biological distinction between infants born at the end of one month and those born at the beginning of the next. International studies have shown that older infants may also benefit from receiving the antibody.

Procurement was planned well in advance, based on the target population defined for the program. Manufacturing and delivery take time, so expanding the target population at short notice is not straightforward once procurement for the relevant winter has already been arranged.

Very positive results during the first winter

Uptake of the antibody program during the 2025–2026 winter was very high, with the vast majority of parents accepting it for their children.

Preliminary findings from Icelandic data indicate a substantial reduction in RSV-related hospital admissions among children under one year of age. There are also indications of fewer primary care visits for respiratory symptoms and reduced use of certain medicines.

These encouraging preliminary findings are consistent with the positive results reported in international studies. Further analysis is ongoing, particularly because the RSV epidemic began later last winter and was smaller than in previous years.

What happens next?

Following the Minister of Health’s decision to secure permanent funding, the preventive program can be planned on a longer-term basis. Its arrangements will be reassessed for the 2027–2028 winter and subsequent seasons.

The Chief Epidemiologist will consider, among other things, whether the target population should be expanded so that more children receive protection during their first RSV season. One option under consideration is to offer the antibody to all infants during their first RSV season, either shortly after birth or before the epidemic begins, depending on when they are born.

This assessment will draw on the latest international research and Icelandic data on hospital admissions, illness and healthcare utilization. Data from last winter are currently being analyzed, and the development of the RSV epidemic this winter will also be monitored.

As antibody procurement must be secured well in advance, decisions about quantities for next winter will need to be based on the best available information at the time, even though the final assessment of the results across both winters will not yet be complete.

Chief Epidemiologist

See also:

• RSV prevention for infants to become a permanent program. Government of Iceland news release, 15 October 2026

• Current guidance from the Chief Epidemiologist on RSV immunization.