Clinical Question
Does a single intramuscular injection of nirsevimab (Beyfortus) reduce the likelihood of hospitalization due to respiratory syncytial virus (RSV) in infants who do not meet criteria for receiving palivizumab?
Bottom Line
In average-risk infants, a single intramuscular dose of nirsevimab reduces the likelihood of hospitalization due to RSV. Although it is not inexpensive, nirsevimab is much less expensive than palivizumab and requires only a single dose. (Level of Evidence = 1b)
Synopsis
Nirsevimab is a monoclonal antibody against RSV that has recently been approved in the United States, Canada, and Europe. The study, which was conducted at 235 sites in France, Germany, and the United Kingdom, identified 8,058 infants born at 29 weeks' gestation or later who were not eligible for palivizumab. Palivizumab is recommended for children at high risk of RSV complications and requires a monthly injection. The patients were recruited during their first winter and randomized to receive nirsevimab (50 mg if they weighed less than 5 kg [11 lb] and 100 mg if they weighed 5 kg or more) or usual care, in open-label fashion. The authors stated that most of the time the admitting physician was not an investigator, although they may have been told of the medication by the parents. The primary outcome was hospitalization for lower respiratory infection with a positive test result for RSV, which occurred in 11 infants in the nirsevimab group and 60 in the usual care group (0.3% vs. 1.5%; P < .001; number needed to treat = 83). Severe RSV infection also occurred less often in the nirsevimab group (0.12% vs. 0.47%; P = .004; number needed to treat = 286). All subgroups of age, weight, sex, gestational age, and timing of randomization had similar benefits. Serious adverse events were rare and similar between groups. According to the American Academy of Pediatrics, the cost of nirsevimab is approximately $495 for one dose.
Study design: Randomized controlled trial (nonblinded)
Funding source: Industry
Allocation: Concealed
Setting: Outpatient (any)
Reference: Drysdale SB, Cathie K, Flamein F, et al.; HARMONIE Study Group. Nirsevimab for prevention of hospitalizations due to RSV in infants. N Engl J Med. 2023;389(26):2425-2435.
Editor's Note: Dr. Ebell is deputy editor for evidence-based medicine for AFP and cofounder and editor-in-chief of Essential Evidence Plus, published by Wiley-Blackwell.
