A study in infants in primary care settings in Spain finds an overall effectiveness of 76% for the monoclonal antibody nirsevimab in preventing medically attended respiratory syncytial virus (RSV) respiratory tract infections. The study is published in Pediatrics.
The study looked at 160 infants 10 months and younger who received the antibody during the 2023–2024 RSV season. All infants were born after April 1, 2023, and received nirsevimab either at birth in hospitals or during a catch-up program before the RSV season started.
The main outcome was medically attended lower respiratory tract infection (LRTI) caused by RSV.
Catch-up reduces load in primary care offices
Overall, 141 infants (88%) received nirsevimab, with 29 (21% of the sample) administered in-hospital during the RSV season, and 112 (79%) through the catch-up program, the authors said. Sixty-seven percent of infant were aged at least 3 months, and most were boys (64%).
RSV was detected in 44 infants (27.5%) included in the study. Within the catch-up group, 37 (28.9%) were positive for RSV.
The overall effectiveness was 75.8% (95% credible interval [CI], 40.4 to 92.7), and 80.2% (95% CI, 44.3 to 95.4) in infants belonging to the catch-up group.
This study demonstrates the effectiveness of nirsevimab in preventing medically attended RSV-LRTI in infants aged younger than 10 months in a large primary care network in Spain, both overall and for the catch-up group.
"This study demonstrates the effectiveness of nirsevimab in preventing medically attended RSV-LRTI in infants aged younger than 10 months in a large primary care network in Spain, both overall and for the catch-up group,” the authors concluded. The authors also said catch-up nirsevimab administration is a powerful tool for reducing primary care burden during RSV season.