Respiratory Syncytial Virus Infection

Health authorities are warning of a looming triad this winter: COVID-19, influenza, and respiratory syncytial virus infections. Their emphasis has been on encouraging vaccination against COVID-19 and influenza. No vaccine is available for prevention of RSV infection, but one monoclonal antibody is available, and several vaccines and more monoclonal antibodies are in development.1

Most children infected with RSV develop a mild illness, but premature infants and children with chronic lung disease (bronchopulmonary dysplasia), congenital heart disease, or immunosuppression can develop lower respiratory disease with bronchiolitis or pneumonia that can result in hospitalization or, rarely, death. Most hospitalizations occur in infants less than 6 months old, and especially in those less than 2 months old. Preterm infants are at highest risk, presumably because they receive fewer maternal antibodies (more than 50% of antibody transfer across the placenta occurs after 32 weeks of gestation) and they have the smallest, most easily obstructed airways. Older and immunosuppressed adults with leukemia or a bone marrow transplant may also become seriously ill with RSV infections.

Palivizumab (Synagis), a monoclonal antibody with RSV-neutralizing activity, was approved by the FDA in 1998 for prevention of RSV infections in high-risk infants and children.2 Pavilizumab has no effect on established RSV disease. In a randomized clinical trial in about 1500 infants and young children who were born prematurely or had bronchopulmonary dysplasia, palivizumab was administered intramuscularly once a month for 5 months, starting at the beginning of the RSV season (usually in October). Hospitalizations for RSV infection occurred significantly less often with palivizumab than with placebo.3

The American Academy of Pediatrics has published guidelines for use of palivizumab prophylaxis and updated them this year in a policy statement on their web site to take into account the effect of the COVID-19 pandemic on the epidemiology of RSV infection, particularly its seasonality.4 The AAP does not recommend palivizumab prophylaxis for otherwise healthy infants born after 29 weeks of gestation or for those with chronic lung disease of prematurity born after 32 weeks. Some pediatricians believe these recommendations are too restrictive.1

Nirsevimab, an extended half-life monoclonal antibody (half-life 85-117 days, which is expected to protect for at least 5 months) and has potent neutralizing activity against RSV has been recommended for approval in the EU.

  1. JB Domachowske et al. The future or respiratory syncytial disease prevention and treatment. Infect Dis Ther 2021; 10(Suppl 1):47.
  2. Palivizumab (Synagis) for prevention of RSV infection. Med Lett Drugs Ther 1999; 41:3.
  3. IMPACT-RSV Study Group. Pavlivizumab, a humanized respiratory syncytial virus monoclonal antibody, reduces hospitalization from respiratory syncytial virus infection in high-risk infants. Pediatrics 1998; 102:531.
  4. American Academy of Pediatrics. Updated guidance for palivizumab prophylaxis among infants and young children at increased risk of hospitalization for respiratory syncytial virus infection. Pediatrics 2014; 134:415; AAP News, August 29, 2022.

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