RSV is a widespread and highly contagious virus. It causes bronchiolitis (infection of the small bronchi) in young children during the winter.
It also affects adults and can be dangerous for the elderly when it degenerates into a respiratory infection. The vaccine was found to be 83% effective in preventing lower respiratory tract infections, according to the U.S. FDA authorization is based on a clinical trial with approximately 25,000 participants, half of whom received the vaccine and half a placebo.