Bronchiolitis: the first preventive treatment for babies arrives in September

Each year 2 to 3% of infants under the age of one are hospitalized for bronchiolitis. This viral infection affects nearly 30% of infants under 2 years of age every winter, i.e. approximately 480,000 cases per year, and RSV is responsible for the majority of bronchiolitis. This Tuesday, the High Authority for Health (HAS) gave the green light for the reimbursement of a preventive treatment against bronchiolitis, Beyfortus developed by the French group Sanofi and the British AstraZeneca.

Beyfortus: a monoclonal antibody in the form of an injection

How does this preventive treatment for bronchiolitis work? “A monoclonal antibody is a type of protein that has been designed to recognize and attach to a specific structure (called an antigen). Nirsevimab attaches to a protein called F protein on the surface of RSV. When nirsevimab is attached to this protein, the virus becomes unable to enter the cells of the body, in particular those of the lungs”, explains the European Medicines Agency. It is therefore not a vaccine but a preventive treatment. Its effectiveness is estimated at 83% against the risk of hospitalization, according to the results of clinical trials conducted in Europe.

Beyfortus will be administered as a single injection into the thigh muscle, before the start of the epidemic season or at birth for infants born during this risk period. The recommended dose is 50 mg for children weighing less than 5 kg and 100 mg for children weighing 5 kg or more.

Soon a new vaccine for pregnant women?

In parallel with this marketing authorization, the Pfizer research laboratory is also developing a vaccine for pregnant women. The latter aims to protect the future baby by antibodies passing through the plasma. The European Medicines Agency has already issued a favorable opinion on July 21 on this future vaccine. As for the HAS, it should soon decide for Europe.