France's annual campaign to prevent bronchiolitis in babies began on Monday, September 14, across mainland France, health authorities confirmed. This year's campaign is marked by the arrival of a new monoclonal antibody, which brings to three the number of protection options against the virus mainly responsible for the illness.
Bronchiolitis is usually a mild illness in infants, but it can sometimes become severe enough to require hospital treatment. The main culprit is respiratory syncytial virus, known as RSV, which spreads widely during the winter months and affects the airways of young children.
France's regional health agency, the Agence Régionale de Santé (ARS), said in a statement that for the 2026-2027 season, the new antibody Enflonsia would complete the existing range of monoclonal antibody immunisation options.
New Antibody From MSD
Enflonsia is made by the American pharmaceutical company MSD. It is approved for babies during the first year they are exposed to the virus and is given as a single injection, with no need to adjust the dose according to the child's weight.
MSD told the French news agency AFP that France had been prioritised for supply of the antibody, and said it had sufficient volumes to meet the needs of patients and health professionals for the 2026-2027 campaign.
France's RSV prevention strategy was first introduced in 2023 to reduce the most severe forms of bronchiolitis. Enflonsia is now the third option available alongside an existing antibody and a maternal vaccine.
Vaccine Offered to Pregnant Women
The existing monoclonal antibody, Beyfortus, was developed by the French pharmaceutical group Sanofi together with the British laboratory AstraZeneca. It is recommended for all newborns during their first winter season, and also for vulnerable children up to the age of two during their second exposure to RSV. It comes in two different dosages.
A separate approach involves a vaccine offered to pregnant women who are due to give birth between September and January, the period when their newborns would be exposed to RSV. The vaccine, Abrysvo, was developed by the American laboratory Pfizer and is given near the end of pregnancy so that the mother's immunity passes to the baby, protecting it from birth up to six months of age.
All three treatments are now reimbursed at 65% by France's national health insurance system, Assurance Maladie, with the remaining cost potentially covered by supplementary health insurers known as mutuelles.
Leading Cause of Winter Hospitalisations
The regional health agency ARS Auvergne-Rhône-Alpes said in its statement that RSV infections represent the leading cause of hospitalisation each year for acute respiratory infection, or bronchiolitis, during the winter season.
