The first syncytial virus immunization campaign prevents 10,000 children from being hospitalized.

The first immunization campaign against respiratory syncytial virus (RSV), which launched in October with the drug nirsevimab to protect children under one year of age from complications such as bronchiolitis or pneumonia, has since prevented nearly 10,000 hospitalizations due to drinking alcohol.

This is evidenced by the assessment carried out by the Ministry of Health together with communities and the National Epidemiological Center of the Carlos III Health Institute on the effectiveness and impact of nirsevimab in preventing serious diseases and not infections, since it is not sterilizing.


The results show that vaccine coverage in some communities exceeded 90% and that immunization with the monoclonal antibody nirsevimab, which Spain became the first country to use on a mass scale, reduced the risk of hospitalization by 83% in minors vaccinated within 6 months.

The number of hospitalizations in children under 1 year of age was reduced by 75% compared to what was estimated to have occurred in this group, meaning nearly 10,000 hospitalizations were averted.

RSV is the leading cause of lower respiratory tract infections in children under one year of age, especially those associated with bronchiolitis and pneumonia; In Spain, infections caused by this virus cause significant strain on the health care system every winter, both in primary care settings and in emergency departments and hospitals.

Nirsevimab began to be given in October last year to children under 6 months born from April 1, 2023 to March 31 of this year, as well as at-risk babies under 2 years of age; A vaccine against RSV for pregnant women is already available for next season, which will provide protection to infants through the passage of antibodies during pregnancy and is awaiting inclusion in the vaccination schedule.

After a period of distortion caused by Covid-19, syncytial, like other viruses, circulated actively again in the 2022–2023 season until it regained its normal pre-Covid behavior and values ​​the following season.

Thus, its impact in this latest season was smaller, according to ISCIII data: until March, RSV left 465,723 infections treated in primary care (almost half of the previous season’s 877,252) and 21,190 hospitalizations, compared with 34,632 cases in 2022. -2023.

The highest rates of hospitalization were observed in children under 1 year of age (3329, 15.7% of the total due to RSV) compared to 13432 (38.8%) in the previous season.