Cause

Respiratory syncytial virus (RSV) is highly contagious, meaning it spreads easily from person to person. There are two main types of RSV and many subtypes (strains). For this reason, you cannot have full immunity to the virus, and you may have many RSV infections throughout life.

People with RSV infection may spread the virus through their secretions (saliva or mucus) when they cough, sneeze, or talk. You can catch the virus by:

• Touching an object or surface contaminated with the virus and then touching your nose, eyes, or mouth without first washing your hands. The virus can survive for more than 6 hours on countertops and other hard surfaces, such as doorknobs, and for 30 minutes on hands, clothing, or tissue.
• Close contact. If an infected person coughs or sneezes near you, you could breathe in RSV that's in his or her saliva or mucus.

The virus spreads easily in crowded settings, such as child care facilities, preschools, churches, and nursing homes. Children attending school often spread the virus to their parents and siblings. The incubation period—the time from exposure to RSV until you have symptoms—ranges from 2 to 8 days, but usually is 4 to 6 days.¹

You are most likely to spread the virus within the first several days after symptoms of RSV infection begin. You remain contagious for up to 8 days or longer. Babies and young children may spread the virus for at least 3 to 4 weeks. Recent research suggests that it may be possible to be a carrier of the virus 3 or 4 months or longer because parts of the virus have been found to remain in some people long after symptoms have disappeared.²

Many different viruses, such as the human metapneumovirus, can cause lower respiratory tract infections in children.³ These viruses can cause symptoms that are similar to an RSV infection.