Two recent studies published in Pediatrics highlight the safety and efficacy of nirsevimab, a long-acting monoclonal antibody, in preventing respiratory syncytial virus (RSV) infections in infants and children. The findings suggest that widespread use of nirsevimab could significantly reduce the burden of RSV-related hospitalizations and severe respiratory illness, particularly in vulnerable populations.
Nirsevimab Well-Tolerated in Immunocompromised Children
An open-label phase 2 trial (MUSIC) assessed the safety and pharmacokinetics of nirsevimab in 100 immunocompromised children aged 24 months and under. The study included children with primary immunodeficiency, previous transplantation, HIV infection, and those treated with immunosuppressive therapies. Follow-up lasted 360 days. Three deaths occurred due to non-RSV lower respiratory tract infection (LRTI). Eight treatment-related adverse events were recorded among six children, but none were classified as serious. Although mean nirsevimab serum concentrations on day 151 were lower in study participants than those in healthy-infant trials, no cases of RSV LRTI occurred through day 151. The authors concluded that nirsevimab was well-tolerated in this high-risk population, with serum concentrations supportive of efficacy.
Significant Reduction in RSV Hospitalizations in Spain
Another study examined the impact of universal nirsevimab administration in newborns up to 6 months of age in Spain. The policy was associated with a 63.1% reduction in acute bronchiolitis-related hospital admissions (95% confidence interval [CI], 60.9% to 65.2%), and a 63.1% reduction in pediatric intensive care unit admissions (95% CI, 58.1% to 67.9%). The study compared RSV hospital admission rates and outcomes at 15 Spanish hospitals during the 2023-2024 season (November through January) and the seasons occurring in 2018 through 2023. The authors noted, "With proper application of immunization strategies, acute bronchiolitis could become a rarely encountered disease in the near future, and the significant health burden of RSV in infants could be greatly reduced."
Wastewater Surveillance as an Indicator of Community Transmission
In related research, a study in Emerging Infectious Diseases found a strong correlation between viral wastewater concentration and positive community respiratory tests for flu viruses, RSV, and SARS-CoV-2. Researchers compared weekly SARS-CoV-2, influenza, and RSV wastewater concentrations with patient test positivity from September 6, 2020, through May 11, 2023, across 48 wastewater treatment plants in Oregon. The authors concluded, "The strength of association observed suggests wastewater surveillance acts as an indicator of community transmission for those pathogens."
