May 03, 2024
Bulletin interne de l'Institut Pasteur
Bronchiolitis: two French studies demonstrate the effectiveness of Beyfortus® in preventing serious illness and reducing hospital admissions among infants
After a 2022/2023 season marked by a severe epidemic of bronchiolitis due to respiratory syncytial virus (RSV), in particular in terms of emergency department visits and hospital admissions, on September 15, 2023 the French Government launched a preventive immunization campaign, administering nirsevimab (Beyfortus®), to protect infants and reduce the circulation of the virus.
To assess the effectiveness (real-world efficacy) of administering the monoclonal antibody nirsevimab (Beyfortus®), in combating the epidemic of RSV bronchiolitis during the 2023/2024 season, two complementary studies were conducted as a collaborative effort by the Institut Pasteur and Santé publique France: one to estimate the effectiveness of nirsevimab against cases of RSV bronchiolitis admitted to intensive care units, and the other to model the impact of the drug in terms of the number of hospital admissions prevented.
The results of both studies confirm the positive impact of nirsevimab on the bronchiolitis epidemic, showing a significant reduction in the number of infants hospitalized and an estimated effectiveness of 76% to 81% for the prevention of RSV bronchiolitis-related hospitalizations in intensive care. In addition, the administration of nirsevimab prevented around 5,800 hospitalizations for bronchiolitis following emergency department visits between September 15, 2023 and January 31, 2024 in mainland France.