Vaccine effectiveness was just as high among participants aged 75 years and older as it was in those 60 and older.
US health officials are eying ways to reduce the spread of the virus over colder months and the holiday season.
The group included patients on dialysis, with lung cancer, on immunotherapy, and who had received solid-organ transplants.
If approved by federal regulators, clesrovimab would be the second prophylactic monoclonal antibody injection against RSV for babies.
The effectiveness of nirsevimab against RSV-associated bronchiolitis leading to pediatric ICU admission was 70%.
There were no significant differences in rates of small-for-gestational-age births or stillbirth.
The results are disappointing compared to the 81% efficacy seen at 3.7 months.
The new recommendations are easier to navigate in clinical settings and focus on older age groups who benefit most.
The total number of hospitalized patients requiring advanced respiratory support was 70% higher in 2022-23.
The rate of mechanical ventilation use was also two- to three-fold higher in 2022-2023 compared with prepandemic years.
