In The News: Nirsevimab Effectiveness Against Severe RSV Holds Up in Real-World Study

A French prospective study revealed nirsevimab protected infants against hospitalization, pediatric intensive care unit admission, and mechanical ventilation due to RSV, reports Medpage Today. The monoclonal antibody was estimated to be 83% effective in infants younger than 12 months of preventing bronchiolitis in the researchers’ logistic regression model. Additionally, it found it was 69.6% effective against bronchiolitis leading to PICU admission, and 67.2% effective against RSV-associated ventilatory support. The researchers stated it was clear nirsevimab is a highly effective, preventative treatment of RSV in young infants.

The study included 690 infants who had been hospitalized for RSV-associated bronchiolitis. Those infants were matched with a control of 345 infants in the same hospital for reasons other than RSV. For infants hospitalized for RSV-associated bronchiolitis, 8.7% were found to have received nirsevimab at least seven days prior to their hospital visit and the control infants with the same timeline of receiving nirsevimab was 28.1%. Similarly, 14% with RSV bronchiolitis requiring PICU admission had received nirsevimab versus 32.2% of control infants, and the comparison for requiring ventilatory support was 14.3% and 30.5%.

Researchers noted their study results should be looked at along with the prelicensure trials of nirsevimab. For instance, the MELODY study found nirsevimab had a somewhat lower efficacy of 74.5% in preventing an RSV-related lower respiratory tract infection in infants that required medical attention, and the HARMONIE study showed nirsevimab was about 83% effective. They further suggested the timings of the assessments may have played a role in these measurements and that its efficacy wanes over time.

In the United States, the Centers for Disease Control and Prevention recommends one dose of nirsevimab for infants younger than eight months of age who were born shortly before or who are entering their first RSV season.

PIDS member Natasha Halasa is quoted in the story. She said, “This is an important study that shows over 80% effectiveness of nirsevimab therapy against RSV-associated hospitalization in a short study period, highlighting the importance of administering this monoclonal to young infants prior to RSV circulation. It is important to ensure that nirsevimab reaches all infants, including those in low- and middle-income countries, where the majority of RSV-attributable deaths occur.”