RSV prevention: A new era for infant protection

Globally, RSV causes millions of respiratory infections each year and is responsible for a large proportion of hospitalizations and deaths among children under five years, with the highest risk concentrated in infants under six months. The disease burden is especially pronounced in low- and middle-income regions, where limited access to healthcare and seasonal surges place substantial strain on pediatric services. Although most of severe cases occur in healthy infants, prevention options have traditionally been restricted to high-risk groups. Recent advances in maternal vaccines and long-acting monoclonal antibodies have broadened the scope of RSV prevention, but questions remain regarding optimal timing, safety, duration of protection, and real-world implementation. Based on these challenges, there is a clear need for comprehensive research into integrated RSV immunoprevention strategies.

In November 2025, the Mexican Association of Pediatrics, in collaboration with a multidisciplinary national panel comprising pediatricians, neonatologists, infectious disease specialists, and obstetric experts, published (DOI: 10.1007/s12519-025-00997-1) a comprehensive position statement in World Journal of Pediatrics. The document synthesizes clinical trials, real-world effectiveness studies, and international policy experience to evaluate maternal RSV vaccination during pregnancy and passive immunization of infants using long-acting monoclonal antibodies. By systematically addressing efficacy, safety, optimal timing, and implementation challenges, the statement provides evidence-based guidance aimed at reducing severe RSV disease and hospitalization in infants across Latin America.

The consensus systematically reviewed evidence from randomized clinical trials, observational studies, and real-world program data to assess two principal RSV prevention strategies. First, maternal immunization with a prefusion F protein RSV vaccine demonstrated high efficacy in preventing severe RSV-related lower respiratory tract infections in infants during the first six months of life. Clinical trials reported protection exceeding 80% during the first three months, with sustained benefit up to six months, supported by efficient transplacental antibody transfer in late pregnancy. Large real-world studies further confirmed substantial reductions in infant hospitalizations and severe disease.

Second, the long-acting monoclonal antibody nirsevimab provided direct passive immunity to infants, achieving 75%-85% effectiveness against RSV hospitalizations across diverse populations, including healthy term and preterm infants. Evidence indicated that a single dose was sufficient to cover an entire RSV season, with favorable safety profiles and significant reductions in intensive care admissions.

Importantly, the analysis clarified that routine coadministration of maternal vaccination and monoclonal antibodies is generally unnecessary, except in specific circumstances where antibody transfer may be compromised. Together, these findings support flexible, evidence-based prevention pathways that can be adapted to local epidemiology, healthcare capacity, and economic considerations.

According to the expert panel, RSV prevention has entered a transformative phase. "For the first time, we have robust tools capable of protecting infants during their most vulnerable months," the authors note. They emphasize that both maternal vaccination and long-acting monoclonal antibodies demonstrate strong benefit-risk profiles when used appropriately. The experts highlight that aligning immunization timing with biological mechanisms of antibody transfer is critical, and that prevention strategies must remain adaptable to national healthcare realities to achieve maximum public health impact.

These findings have significant implications for both public health policy and clinical practice. The implementing maternal RSV vaccination or infant monoclonal antibody programs can markedly reduce hospital admissions, healthcare costs, and infant mortality associated with RSV. The evidence supports prioritizing prevention in the first six months of life, when disease severity is greatest. In middle-income regions, maternal vaccination may offer a particularly feasible and cost-effective approach, while monoclonal antibodies provide an essential alternative for infants who miss prenatal protection. Together, these strategies offer a scalable pathway toward reducing the global burden of RSV and strengthening early-life respiratory health.