Respiratory Syncytial Virus (RSV) is a common respiratory illness that can cause mild symptoms similar to a cold, but it can also be dangerous, even deadly for those who are more vulnerable.
Right now in the U.S., RSV activity is low, but October is when the virus typically starts spreading.
“It’s the leading cause of hospitalizations in kids less than one year of age,” explained Dr. Juanita Mora, national medical spokesperson for the American Lung Association.
Mora said RSV symptoms may start mild -- with a runny nose and high fevers -- but it can travel to the lungs and cause babies and young children to be at risk for illnesses like pneumonia.
She said if a child is having labored breathing, shortness of breath, wheezing, a worsening cough or signs of dehydration, like a lack of wet diapers, it’s time to take them to the emergency room.
But she said there is a way to protect against severe disease: the RSV vaccine.
The Centers for Disease Control and Prevention says it can be given during weeks 32 and 36 of pregnancy.
Or an infant RSV antibody can be given to the baby after birth.
“We saw from the 2024-2025 data that by giving protection to these babies, we were able to reduce hospitalization by 50%,” Mora said.
Not everyone who contracts RSV will go to a doctor, so it’s hard to know the exact number of people who were sick.
But last season, the CDC data estimates show that from Oct. 1, 2024, through May 3, 2025, there were up to 6.5 million RSV outpatient visits, up to 350,000 hospitalizations and up to 23,0000 deaths due to RSV.
This season, the agency expects that peak weekly hospitalization rates across all age groups due to RSV will be similar.
“Let’s protect the village to help protect these babies,” Mora said.
While the RSV vaccine is not currently an annual vaccine, the CDC recommends a single dose of it for all adults ages 75 and older, and those between the ages of 50 and 74 who are at increased risk for severe RSV.