RSV cases on the rise as COVID-19 restrictions ease, NIH says

U.S. health officials are asking Americans to be watchful as COVID-19 precautions are being lifted, paving the way for another common virus to take hold.

According to the National Institutes of Health, respiratory syncytial virus, or RSV, infects the cells that line the lungs and breathing passages. Symptoms are similar to the common cold such as a runny nose, loss of appetite, and coughing or wheezing. Symptoms usually stay mild in older children and adults though some people are at risk of more serious disease including infants, older adults and people with a weakened immune system. 

Scientists say almost everyone catches RSV before the age of 2 as it’s one of the most common causes of illness in children. 

RELATED: Doctors are seeing rise in RSV and other respiratory viruses in young children

But unlike many other respiratory viruses, people can catch RSV over and over again.

"RSV has a number of ways of evading the immune system," Dr. Barney Graham, a physician who studies viruses at NIH, said in a news release. "So people are re-infected with RSV on average every three to 10 years."

NIH says RSV is usually more common in the fall, winter and spring. But infections increased over the summer as states eased up COVID-19 restrictions. According to a chart from the U.S. Centers for Disease Control and Prevention, there were more than 3,000 cases in the U.S. in early August 2021 compared to less than two dozen in early January 2021, when restrictions were still in place in many cities and states.

Scientists urge people to watch for symptoms. If they get worse over time or a person is having trouble breathing or drinking fluids, they should see a health care provider right away given that a blood test can show if a person has RSV or another virus. 

RELATED: Fully vaccinated people half as likely to develop long-term COVID-19, study suggests

RSV is also contagious as it can travel in droplets from a cough or sneeze. It can also remain on commonly touched surfaces such as doorknobs and tables. 

In terms of prognosis, NIH says most people who get a mild case of RSV feel better in less than two weeks but can still spread the virus even after symptoms disappear. 

As for medicine, health officials say over-the-counter fever or pain relievers may help reduce symptoms. Hospitalization may be required for more serious cases.

A vaccine isn’t available but NIH researchers are working to develop one and advise people to practice good hygiene, such as proper hand-washing, to avoid getting infected. There is no approved treatment for RSV, although a once-monthly injection of an antibody-based medicine is sometimes prescribed before and throughout RSV season to help prevent severe RSV lung problems in premature infants and other babies at risk of serious disease.

Among U.S. kids under age 5, RSV typically leads to 2 million doctor-office visits each year, 58,000 hospitalizations and up to 500 deaths — higher than the estimated toll on kids from COVID-19.

The Associated Press contributed to this report. This story was reported from Los Angeles.