Respiratory syncytial virus (RSV) infects almost all children by the age of 2, and reinfection throughout life is common.¹ The first RSV infection is usually the most severe. The virus spreads easily and is extremely difficult to completely avoid. Babies and young children who are in day care centers or frequently in public places are most likely to become infected, especially during the peak season. Older brothers and sisters in school often become infected with the virus and spread it to other household members, including babies and preschoolers. Sharing food, touching objects that are contaminated with the virus, and not washing hands can lead to RSV infection. Older adults living in nursing homes or other group environments also have a higher risk of becoming infected with RSV.

Babies between 2 months and 7 months of age have the highest incidence of RSV infection affecting the lower respiratory tract. Reinfection with another type or strain of RSV can occur within weeks. However, later infections are usually less severe.⁴

With RSV infections, there is an increased risk of having complications, especially in certain babies and young children and adults older than 65. The complications bronchiolitis and pneumonia occur slightly more often in boys than in girls.⁴

You can get RSV throughout your life because there are two different types and many subtypes (strains) of the virus, meaning you can never have complete immunity.