What Is RSV and How Do Kids Get It? CDC Warns of Spike in Virus Affecting Children

The U.S. is experiencing a summer surge in RSV—a common virus that can cause serious illness especially in infants and older adults.

Last month, the Centers for Disease Control and Prevention (CDC) issued a health advisory warning clinicians about an increase in RSV activity across parts of the southern U.S.

The CDC said it's encouraging more testing for RSV, also known as respiratory syncytial virus, among people who turn up at medical centers with a respiratory illness, but who test negative for COVID.

What Is RSV?

RSV is a virus that usually causes mild, cold-like symptoms in people who catch it. However, it is also the most common cause of bronchiolitis—an inflammation of the airways—and pneumonia in children under the age of 1.

Some patients, particularly older adults and children under 6 months of age, may need to be hospitalized if they are having trouble breathing or are dehydrated after an RSV infection. In severe cases, they may require supplemental oxygen.

Like the flu, RSV spreads more often at certain times of the year, and in most regions of the U.S. that's during the fall, winter and spring.

Dr Allison Bartlett, a pediatric infectious disease doctor at the University of Chicago, told ABC News it's "unusual" for RSV to be spreading at this time of year.

She added: "All of the actions we took to stop the spread of COVID effectively prevented RSV as well. Now that we have relaxed some of these strategies, RSV is back."

How Does It Spread?

People can become infected with RSV if virus droplets from someone's cough or sneeze enter their eyes, nose, or mouth. It can also spread through contact with surfaces, for example if someone touches a doorknob and then their face without washing their hands in between.

Once infected, people may be contagious for three to eight days. But people with weakened immune systems and some infants may spread the virus for as long as four weeks even after they have stopped showing symptoms.

RSV can live on hard surfaces, such as tables or crib rails, for many hours, the CDC states. On softer surfaces, it lives for a shorter amount of time.

Preventing the spread of RSV involves frequently cleaning surfaces including doorknobs and mobile devices; washing hands often with soap and water for at least 20 seconds; and avoiding contact with sick people.

The CDC adds that people with cold-like symptoms should avoid interacting with children at high risk of severe RSV disease, including premature infants, children under two with chronic lung or heart conditions, or those with weak immune systems.

Take Care Around High-Risk Children

If this isn't possible, people should carefully follow preventive measures such as regularly washing hands and refraining from kissing high-risk children.

People usually show symptoms within four to six days of getting infected. The symptoms include a runny nose, lack of appetite, coughing, sneezing, fever and wheezing.

In very young infants, the symptoms may also include irritability, decreased activity and breathing difficulties.

Nearly all children get an RSV infection by the time they are 2 years old. The CDC states that an estimated 58,000 children younger than 5 years old are hospitalized with the virus each year in the U.S.

Washing child's hands
A file photo shows a child and an older person washing their hands with soap. The CDC states RSV can live on hard surfaces for many hours. adiekoetter/Getty