Today, the World Health Organization (WHO) published its first-ever position paper on immunization products to protect infants against respiratory syncytial virus (RSV) – the leading cause of acute lower respiratory infections in children globally.
Every year, RSV causes about 100 000 deaths and over 3.6 million hospitalizations in children under the age of 5 years worldwide. About half of these deaths occur in infants younger than 6 months of age. The vast majority (97%) of RSV deaths in infants occur in low- and middle-income countries where there is limited access to supportive medical care, such as oxygen or hydration.
Published in the Weekly Epidemiological Record (WER), the position paper outlines WHO recommendations for two immunization products: a maternal vaccine that can be given to pregnant women in their third trimester to protect their infant and a long-acting monoclonal antibody that can be administered to infants from birth, just before or during the RSV season.
"RSV is an incredibly infectious virus that infects people of all ages, but is especially harmful to infants, particularly those born premature, when they are most vulnerable to severe disease," says Dr Kate O'Brien, Director of Immunization, Vaccines, and Biologicals at WHO. "The WHO-recommended RSV immunization products can transform the fight against severe RSV disease, dramatically reduce hospitalizations, and deaths, ultimately saving many infant lives globally."
RSV usually causes mild symptoms similar to the common cold, including runny nose, cough and fever. However, it can lead to serious complications – including pneumonia and bronchiolitis – in infants, young children, older adults and those with compromised immune systems or underlying health conditions.
Two immunization products to protect against RSV
In response to the global burden of severe RSV disease among infants, WHO recommends that all countries introduce either the maternal vaccine, RSVpreF, or the monoclonal antibody, nirsevimab depending on the feasibility of implementation within each country's existing health system, cost-effectiveness and anticipated coverage. Both products were recommended by the Strategic Advisory Group of Experts on Immunization (SAGE) for global implementation in September 2024. In addition, the maternal vaccine received WHO prequalification in March 2025, allowing it to be purchased by UN agencies.
WHO recommends that the maternal vaccine be given to pregnant women during the third trimester of pregnancy, from week 28 onwards, to optimize for the adequate transfer of antibodies to their baby. The vaccine may be given during routine antenatal care, including at one of the 5 WHO-recommended antenatal care visits in the third trimester or any additional medical consultations.
The second WHO-recommended immunization product, nirsevimab, is given as a single injection of monoclonal antibodies that starts protecting babies against RSV within a week of administration and lasts for at least 5 months, which can cover the entire RSV season in countries with RSV seasonality.
WHO recommends that infants receive a single dose of nirsevimab right after birth or before being discharged from a birthing facility. If not administered at birth, the monoclonal antibody can be given during the baby's first health visit. If a country decides to administer the product only during the RSV season rather than year-round, a single dose can also be given to older infants just before entering their first RSV season.
The greatest impact on severe RSV disease will be achieved by administering the monoclonal antibody to infants under 6 months of age. However, there is still a potential benefit among infants up to 12 months of age.
WHO regularly issues updated position papers on vaccines, combinations of vaccines and other immunization products against diseases that have major public health impact. These papers focus primarily on the use of vaccines in large-scale vaccination programmes. The new position paper aims to inform national public health policymakers and immunization programme managers on the use of RSV immunization products in their national programmes, as well as national and international funding agencies.
