The Global Burden of RSV in Infants
RSV is a common respiratory virus that typically presents with mild, cold-like symptoms such as a runny nose, cough, and fever, according to the Centers for Disease Control and Prevention (CDC). However, in infants, young children, older adults, and individuals with compromised immune systems or underlying health conditions, it can escalate to severe complications like pneumonia and bronchiolitis.
Alarmingly, about half of all RSV-related infant deaths occur in babies younger than six months, with a staggering 97% of these fatalities concentrated in low- and middle-income countries. This stark disparity underscores the urgent need for effective prevention strategies in vulnerable populations.
Dual-pronged Approach to Protection
The new WHO position paper, published in the Weekly Epidemiological Record (WER), details recommendations for two distinct immunization products:
- Maternal Vaccine (RSVpreF): This vaccine can be administered to pregnant women during their third trimester. The goal is to transfer protective antibodies from the mother to her unborn child, providing passive immunity to the infant from birth.
- Long-acting Monoclonal Antibody (nirsevimab): This antibody can be given directly to infants from birth, or just before or during the RSV season. A single dose offers protection for at least five months.
Dr. Kate O’Brien, WHO Director of Immunization, Vaccines, and Biologicals, expressed optimism about these new tools. "The WHO-recommended RSV immunisation products can transform the fight against severe RSV disease, dramatically reduce hospitalisations and deaths, and ultimately save many infant lives globally," she stated.
Recommendations for National Implementation
In light of the substantial global burden of severe RSV disease in infants, WHO strongly recommends that all countries consider introducing either the maternal vaccine (RSVpreF) or the monoclonal antibody (nirsevimab) into their national immunization programs. The choice between the two products should be guided by factors such as the feasibility of implementation within existing health systems, cost-effectiveness, and anticipated coverage rates.
Both products received recommendations for global implementation from the Strategic Advisory Group of Experts on Immunization (SAGE) in September 2024. Additionally, the maternal vaccine obtained WHO prequalification in March 2025, facilitating its procurement by UN agencies.
For the monoclonal antibody, WHO advises administering a single dose of nirsevimab to infants immediately after birth or before discharge from a birthing facility. If not given at birth, it can be administered during the baby's first health visit. For countries opting for seasonal administration rather than year-round, a single dose can also be given to older infants just before they enter their first RSV season.
This new position paper is intended to serve as a vital resource for national public health policymakers, immunization program managers, and national and international funding agencies, guiding the strategic integration of RSV immunization products into their national health initiatives.