In a major step to combat a leading threat to infants, the World Health Organization (WHO) has released its first-ever guidance on immunizing babies against Respiratory Syncytial Virus (RSV). This virus is known as the primary cause of severe lower respiratory infections in children globally, claiming approximately 100,000 lives and causing over 3.6 million hospitalizations annually among children under five. Alarmingly, half of these deaths occur in infants younger than six months, with a staggering 97% happening in low- and middle-income countries where critical medical support like oxygen is often scarce.
Published in its Weekly Epidemiological Record, the WHO position paper formally endorses two powerful new immunization strategies to protect vulnerable infants:
1. A Maternal Vaccine (RSVpreF): This should be administered to pregnant women during their third trimester (from week 28 onwards), this vaccine will boost the mother’s antibodies, which are then passed to her developing baby, offering crucial early protection after birth. It can be integrated into routine prenatal care visits.
2. A Long-Acting Monoclonal Antibody (Nirsevimab): This must be given as a single injection to infants, this product will help provide rapid defense within a week and lasts at least five months – typically covering an entire RSV season. WHO recommends administration right after birth or before discharge from the birthing facility. If missed then, it can be given at the baby’s first health check. For seasonal use, a dose can also be given just before an infant’s first RSV season.
“RSV is incredibly infectious and harms people of all ages, but infants, especially those born premature, face the gravest risk of severe illness. These WHO-recommended tools represent a potential transformation in our fight against severe RSV disease. They promise to dramatically cut infant hospitalizations and deaths worldwide, saving countless young lives.” Dr. Kate O’Brien, WHO Director of Immunization, Vaccines, and Biologicals stated.
While RSV often causes mild cold-like symptoms, it can escalate into life-threatening complications like pneumonia and bronchiolitis, particularly in infants, young children, the elderly, and those with weakened immune systems.
The WHO advises countries to choose the product best suited to their healthcare systems, considering implementation feasibility, cost-effectiveness, and potential coverage. Both options received a global implementation recommendation from WHO’s Strategic Advisory Group of Experts on Immunization (SAGE) last September. The maternal vaccine also achieved WHO prequalification in March, 2025 facilitating procurement by UN agencies.
Nirsevimab protection is most effective for newborns under six months old, but the advantages last up to 12 months. This strategy seeks to provide national health authorities and immunization program administrators with the evidence they need to incorporate these critical tools into their public health policies, thereby minimizing the devastating worldwide impact of RSV on the youngest and most vulnerable.
Source: WHO
