Real-world efficacy data from Spain indicate that the RSV drug nirsevimab (Beyfortus) is at least 70% effective at preventing RSV hospitalizations in infants under 9 months old, according to new research in Eurosurveillance.
Spain was one of the first countries to introduce nirsevimab as universal RSV prophylaxis (prevention) into its national immunization program for all infants born on April 1, 2023, and after.
In the study, researchers assessed the effectiveness of nirsevimab against hospital admission for RSV for babies across nine hospitals in three Spanish regions. The surveillance period lasted from October 1, 2023, to between December 31, 2023, and January 10, 2024, depending on the hospital.
Easing pressure on healthcare systems
Overall, 166 infant admissions for lower respiratory tract infections included, of which 95 were positive for RSV and 73 were aged 0 to 3 months.
Among all 95 RSV cases, 56 (59%) had been immunized, the authors said.
The immunisation with nirsevimab is expected to alleviate the high pressure on the healthcare systems, especially during winter periods.
Effectiveness against hospitalization was estimated for each region and was as follows: 69.3% (95% confidence interval [CI], 36.4% to 86.2%), 86.9% (95% CI, 77.1% to 92.9%) and 97.0% (95% CI, 87.7% to 99.6%) in Valencia, Murcia and Valladolid, respectively.
"Our estimates indicate that nirsevimab effectiveness was greater than 70% in infants under 9 months of age who were candidates to receive the immunisation. The lack of protection in the RSV-negative hospitalisations supports the estimates," the authors wrote. "In Spain, 3.2 per 100 infants under 6 months of age are hospitalised for an RSV bronchiolitis. The immunisation with nirsevimab is expected to alleviate the high pressure on the healthcare systems, especially during winter periods."