Hospitals across the country have been experiencing strain due in part to an influx of a high number of patients with respiratory syncytial virus (RSV). In December, when combined with other illnesses and injuries, approximately 80 percent of U.S. hospital inpatient beds were occupied.

RSV, a highly contagious virus, is not new. According to the U.S. Centers for Disease Control, it was discovered in 1956 and has since been recognized as one of the most common causes of childhood illness.

Get more HMS news here

Two clinicians at Harvard Medical School’s Center for Primary Care weighed in recently on why RSV infections are on the rise.

“RSV is a common virus ubiquitous in our world,” said Niraj Sharma, HMS assistant professor of medicine and internal medicine-pediatric medicine physician at Brigham and Women’s Hospital.

“For many adults and children, it presents as a common cold. We may not even realize that we have it,” Sharma said.

Given how common RSV is, it has many people wondering why the current surge is happening at all.

Science & Medicine, Delivered

Harvard Medicine magazine in your inbox

“We are not certain why RSV cases are rising. It has been suggested that everyone has lost immunity over the past two years, but that doesn’t actually make sense for a virus that’s so common,” said Kirsten Meisinger, HMS instructor in medicine at Cambridge Health Alliance and clinical lead for leadership and system transformation at the Center for Primary Care.

“COVID seems to have altered the timing of when common infections are happening, but we still have so much to learn about why,” she said.

What to do if you think you have RSV

RSV symptoms include a runny nose, coughing, and a low-grade fever. The only way to be certain that symptoms are caused by RSV, however, is through a test in a doctor’s office. In most cases, these kinds of viral infections are treated similarly.

“Rest, lots of fluids, and healthy food may be enough to get through any common viral infection.” Meisinger said.

“If there’s any concern, contact your primary care physician first,” Sharma advised.

He said to start with a phone call. Many practices have a phone system that allows patients or their guardians to speak with a clinician 24/7. This conversation can offer critical guidance on whether a trip to the emergency room is necessary or if an appointment can be made for the next day.

How is RSV different from other common viruses?

Certain populations are at risk for severe illness with RSV, including children under age 1, adults 65 and older, and those with chronic lung conditions, including asthma.

A report published in JAMA Network found that RSV mortality rates were the highest among adults aged 65 and older and the next highest rate was among children younger than 1 year. RSV mortality was five-fold higher than influenza mortality among children younger than 1 year.

“Ninety-seven percent of infants get RSV by age 2,” Meisinger said. “RSV is incredibly contagious and there is no vaccine, which is part of why it can cause such widespread disease.”

A vaccine for RSV is currently under development, but is not yet approved. In the meantime, it is still helpful for individuals to get vaccinated against flu and COVID-19 to protect public health.

“It’s critically important, especially if you or your child have a condition like asthma,” said Sharma. “The vaccine may not prevent illness, but it is our best protection against severe illness.”

Many of the precautions the public learned as a result of the pandemic hold true for RSV. It’s important for people to wash hands often and consider wearing a mask if they have an underlying medical condition. When sick, it’s best to stay home and distance from others.

“If you’re concerned about your health, don’t make decisions based on the pressure you’re receiving from others,” Sharma cautioned. “Do what you need to do to keep yourself and loved ones safe.”