WHO Endorses First-Ever RSV Vaccination Guidance to Protect Infants

In a significant move to curb the global burden of respiratory syncytial virus (RSV), the World Health Organization (WHO) has released its first-ever position paper on immunization strategies to protect infants from this highly infectious disease. Published in the Weekly Epidemiological Record (WER), the paper marks a historic milestone in global health, outlining recommendations for two key immunization products: a maternal vaccine and a long-acting monoclonal antibody.

The announcement comes as part of WHO’s broader effort to reduce child mortality, particularly in low- and middle-income countries where the impact of RSV is most severe.

A Leading Cause of Infant Mortality

RSV is a major cause of acute lower respiratory infections, such as pneumonia and bronchiolitis, in children. Globally, it is responsible for approximately 100,000 deaths and 3.6 million hospitalizations annually among children under five. Infants younger than six months are the most vulnerable, accounting for nearly half of these deaths. Tragically, 97% of RSV-related infant deaths occur in low- and middle-income countries where access to supportive care like oxygen therapy or IV hydration is limited.

Dr. Kate O’Brien, WHO’s Director of Immunization, Vaccines, and Biologicals, emphasized the urgency:

“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. The WHO-recommended RSV immunization products can transform the fight against severe RSV disease, dramatically reduce hospitalizations and deaths, and ultimately save many infant lives globally.”

Two Immunization Products: A Dual Approach

The WHO position paper offers a dual strategy to address the RSV burden through two promising products:

1. Maternal Vaccine (RSVpreF)

This vaccine is administered to pregnant women during the third trimester (from 28 weeks onwards). The goal is to ensure the transfer of protective antibodies to the unborn child. The vaccine can be given as part of routine antenatal care, ideally during one of WHO's recommended antenatal visits or additional consultations.

The maternal vaccine, RSVpreF, received WHO prequalification in March 2025, making it eligible for procurement by United Nations agencies and other global partners. The strategy provides passive immunity to newborns, protecting them during their first months of life when they are most at risk.

2. Monoclonal Antibody (Nirsevimab)

Nirsevimab is a long-acting monoclonal antibody given as a single injection to infants. It begins to work within a week and provides protection for at least five months, typically long enough to cover an entire RSV season.

WHO recommends administering nirsevimab:

• Immediately after birth or before discharge from a birthing facility,

• During the infant’s first postnatal healthcare visit if not given at birth,

• Just before RSV season for older infants who have not yet been exposed.

Although the greatest benefit is seen in infants under 6 months, the product can still offer protection for infants up to 12 months of age, especially during their first exposure to RSV.

Implementation Depends on Local Feasibility

WHO’s position paper encourages countries to select the most suitable product based on their healthcare system’s capacity, cost-effectiveness, and population coverage. The Strategic Advisory Group of Experts on Immunization (SAGE) approved both products for global implementation in September 2024. The inclusion of these options is seen as a flexible approach, allowing countries to tailor immunization programs to their public health priorities and resource levels.

RSV: A Common Yet Dangerous Virus

Although RSV typically causes mild symptoms—runny nose, cough, low-grade fever—it can escalate rapidly in infants and other vulnerable groups, leading to life-threatening respiratory illnesses. Premature infants, children with congenital heart or lung conditions, and those with weakened immune systems face particularly high risks of severe complications.

Older adults, especially those with chronic conditions, are also susceptible to RSV, though the new guidance focuses primarily on infant immunization strategies to reduce early-life mortality.

Public Health Impact and Future Directions

The new WHO recommendations are part of a broader strategy to reduce childhood mortality, one of the primary targets of Sustainable Development Goal 3 (SDG3). The implementation of these immunization products can not only alleviate the burden on healthcare systems—by preventing hospitalizations and the need for intensive care—but also ease emotional and financial strain on families.

The position paper aims to guide:

• National policymakers setting immunization agendas;

• Health program managers integrating RSV strategies into maternal and child health services;

• Funding agencies, including international partners and governments, to support the rollout of RSV immunization in high-burden regions.

Looking Ahead

This policy paper is expected to pave the way for broader availability and uptake of RSV immunization products. WHO will continue to provide technical support, monitor real-world impact, and update its guidance as more data becomes available.

The initiative underscores WHO’s commitment to advancing equitable access to life-saving interventions, especially in underserved populations where the stakes are highest.