What Is RSV?

Every fall and winter, colds, cases of flu, and a common illness called respiratory syncytial virus (aka RSV) start to make their way around the country leading to sniffles, coughs, and — in some more serious cases — hospitalizations. RSV, specifically, tends to be a big worry for new parents and older adults: Young babies and seniors are at an increased risk of severe disease, but people of all ages can get the virus. But what exactly is RSV and what do you need to know about keeping yourself and others safe?

Here, infectious disease physicians and pediatricians weigh in on what you need to know.

What is RSV?

In short, RSV, which stands for respiratory syncytial virus) is a very common respiratory virus.

Before the COVID-19 pandemic, RSV tended to occur in reliable waves of infection every winter in the United States, starting in November, and running through March, says Mary T. Caserta, M.D., a pediatric infectious disease specialist at The University of Rochester Medical Center. Now, it’s more unpredictable, with outbreaks happening all throughout the year.

Usually, RSV is mild. If you get it, you may have cold-like symptoms for a week or two.

But sometimes, RSV can be serious. All are susceptible to falling ill from RSV — there’s no vaccine, simply being around others is a risk factor for getting it, and you can get it more than once — but both older adults and young children are at an increased risk for severe disease, in part due to immature or weakened immune systems.

RSV in children

It’s true: Anyone can get RSV, but it is incredibly common and can be riskier for young kids. “What we know is that most kids will be infected by the time they're two,” says Shaila Siraj, M.D., a pediatric hospitalist at Johns Hopkins All Children’s Hospital.

“RSV really is the main pathogen causing respiratory disease in babies,” adds Caserta.

Again, most of the time, infections are mild — a runny nose, a decrease in appetite, fussiness in babies, or a cough.

But RSV can be dangerous for some. In fact, one to two of every 100 children under 6 months (and about 58,000 kids under 5) who get RSV may require hospitalization for oxygen, intubation, or ventilation, estimates the Centers for Disease Control and Prevention (CDC).

“RSV can start out looking like your typical cold — what we call a mild upper respiratory tract infection,” explains Joanna Parga-Belinkie, M.D., an attending neonatologist in the Division of Neonatology at Children's Hospital of Philadelphia. (This essentially means it starts in the nose.) “What we worry about with RSV is that it can progress to a more severe lower respiratory tract disease, which can lead to things like bronchiolitis, inflammation of the smaller airways in the lungs, and pneumonia.”

In fact, RSV is the most common cause of both bronchiolitis and pneumonia (an infection of the lungs) in U.S. babies under a year.

Kids at the most risk for severe illness from RSV: premature babies and babies under 6 months, kids under 2 with chronic lung disease or congenital heart disease, kids with weakened immune systems, and kids with neuromuscular disorders.

Experts aren’t entirely sure why RSV can be more serious in young babies, but it could be due to a mix of anatomy (when small airways swell, there’s not a lot of room, so babies can have trouble breathing), and RSV likely being a baby’s first infection, leading, perhaps, to a heightened immune response, Caserta says.

How to prevent RSV

When it comes to viral prevention, in general, vaccination is important. And while there’s no vaccine for RSV, “we always advocate for making sure that everybody in the family is vaccinated for what they can be vaccinated for,” says Parga-Belinkie. This means ensuring that those who spend time around your child are vaccinated against the flu, COVID, and other respiratory illnesses. Says Parga-Belinkie: “It’s called cocooning; if you get everybody else vaccinated around the baby, there’s less of a chance that the baby's going to get any sort of infection.”

She also recommends avoiding unnecessary travel with infants (and seeing lots of people who may or may not have RSV and may or may not be spreading it) and practicing good hand-washing.

Cough hygiene — into your elbow, away from others — and respiratory etiquette (masking if need be, avoiding people if you’re sick) matter, too.

Additionally, Parga-Belinkie says “we do recommend for those families able to, to breastfeed because that can offer some immunity and protection to the baby.”

How to treat RSV

There’s no one treatment for RSV, though researchers and pharmaceutical companies (Pfizer, for one) are working to develop vaccines for it and there are hopefully exciting new treatments on the horizon.

The good news: Most RSV infections clear on their own in a week or two.

For RSV in babies, symptom management at home often includes the use of a suction device (NoseFrida!) to remove excess mucus that might build up or in a baby older than 2 months, infant Tylenol to manage a fever. (A fever in a baby under two months is considered an emergency and you should always bring them to the emergency room.)

Hydration is also key — keeping up with breastfeeding, formula, or, if your baby is 6 months or older, water.

If you suspect your baby is dehydrated (for infants, six or fewer wet diapers a day) or if they are having trouble breathing, they may need to be hospitalized for additional care, such as oxygen or respiratory support.

The good news: Even in the case of hospitalization, most improve children with supportive care in a few days time, the CDC says.

The bottom line

RSV is a common respiratory virus in babies and young children, with most kids contracting the illness before the age of 2. Often, it’s mild, but sometimes — and in particularly at-risk populations — it can be serious. Taking preventative measures and knowing how to spot more serious symptoms like having trouble breathing is key to getting your child the support they need.

Experts:

Mary T. Caserta, M.D., a pediatric infectious disease specialist at The University of Rochester Medical Center.

Shaila Siraj, M.D., a pediatric hospitalist at Johns Hopkins All Children’s Hospital.

Joanna Parga-Belinkie, M.D., an attending neonatologist in the Division of Neonatology at Children's Hospital of Philadelphia.