Bronchiolitis is a common viral infection that affects the small airways in the lungs, often seen in very young children. Each winter, about one in three infants in France is infected with bronchiolitis. While the infection typically resolves on its own within a few days, it can cause breathing difficulties. Around 2 to 3 out of every 100 infants under one year old may need hospitalization, with most of these being under six months old. Although adults and older children usually don’t suffer from severe forms of the illness, they can carry and spread the virus after being exposed in places like daycare centers, schools, or public areas. Measures such as proper room ventilation, handwashing, and wearing masks are important for prevention, but they may not always be enough to protect the most vulnerable infants. A maternal vaccine called Abrysvo helps protect newborns by passing antibodies from the mother to the baby. This vaccine is typically administered to pregnant women during the eighth month of pregnancy, specifically between the 32nd and 36th weeks of amenorrhea (the time since the last menstrual period). The bivalent vaccine enables the mother’s body to produce specific antibodies against the virus, which then cross the placenta to reach the baby before birth. This provides the child with immediate protection that lasts between three and six months. To ensure the antibodies are fully transferred, the vaccine should be given at least fourteen days before delivery. It is provided free of charge in the maternity ward and fully reimbursed by the Maternity Insurance at pharmacies. Any side effects are generally mild and temporary, such as redness or sensitivity at the injection site and headaches. Another option for protecting newborns is the use of monoclonal antibodies, which provide direct immunity to the baby. If a mother cannot be vaccinated during pregnancy or if a parent prefers this method, a monoclonal antibody injection is an effective alternative. Treatments such as Beyfortus or Enflonsia provide the infant with ready-to-act antibodies against the virus. The injection is usually given in the maternity ward before the baby goes home. Protection reaches its peak six days after the injection and lasts at least five to six months. This method is also preferred if the mother is immunocompromised. At the maternity ward, this care is provided without upfront cost, and the Health Insurance covers 65% of the cost at the local pharmacy, with most mutuals covering the remainder. Common reactions in the infant are usually limited to a skin rash, a slight fever, or a local redness. The decision between using the maternal vaccine or monoclonal antibodies should be made in consultation with a healthcare provider. Some parents prefer to vaccinate the mother to avoid giving an additional injection to the newborn in the first days of life, while others choose the baby's preventive treatment, reassured by the experience with Beyfortus since 2023. The High Authority for Health emphasizes that any health decision should be made in trust with your doctor, midwife, or the maternity team. It is important to take the time to ask all your questions and consider what matters most to you so that you can welcome your child with peace of mind.