RSV is a common respiratory virus that causes cold-like symptoms in most people. Adults can usually brush off RSV in a week or two. But it’s a different story for children under age 1. The virus is usually behind bronchiolitis (inflammation of the small airways in the lung) and pneumonia (infection of the lungs) for children who haven’t reached their first year, according to the Centers for Disease Control and Prevention . An estimated 58,000 children under 5 are hospitalized every year in the United States because of RSV infection, according to the CDC. Between 100 and 500 children under 5 die of RSV every year. The virus can give children a fever, a runny nose and a cough and cause difficulty breathing. So how do you tell the difference between RSV and the flu or covid-19? “It’s almost impossible,” said Thomas Murray, an associate professor at the Yale University School of Medicine who specializes in pediatric infectious disease. There is a rapid antigen test, but it can’t be administered at home like coronavirus tests. Murray said RSV, unlike the coronavirus, spreads more via surfaces than droplets. He suggests sanitizing high-touch areas such as toys, doorknobs, kitchen counters and bathroom sinks, along with washing your hands. “Where these infections might have been spread out over time, they’re happening all at once now,” said Céline Gounder, a senior fellow at the Kaiser Family Foundation and infectious-disease specialist. Simple physics is another reason children under age 1 struggle with RSV: They have smaller airways, so they are more likely to need oxygen or treatment, because inflammation affects them more severely.

Why is RSV so bad this year?

Experts agree that people did the right thing by wearing masks and socially distancing because of the coronavirus, but the lack of interaction with germs also made our bodies far less resilient to disease. Small interactions with viruses prime our system to better handle future exposures to viruses. After years of masking in schools and distancing, children have fewer biological defenses to fend off multiple viruses at once. Most children under 3 have never known a world without covid-19, so neither have their immune systems. Part of this is also a numbers game — the more months the viruses are prevalent, the better chance an immune system can be caught off-guard. All that means young children are nearly helpless against all the respiratory viruses that thrive during winter. Elizabeth Mack, head of the pediatric critical-care unit at the Medical University of South Carolina, said she gets calls from staffers in neighboring states asking whether she has pediatric beds in her facility. “The children’s hospitals in this country are drowning right now,” she said. Mack said RSV is the most common reason infants are hospitalized. The season for RSV usually starts in October, she said. This year, the wave began in September or even August. “It seems to be back early,” she said. There’s no research to show that RSV has changed. Instead, we have. Cases beginning a month or so earlier may not sound like a lot, Mack said, but there are other disruptive forces beyond anyone’s control: She is expecting a worse flu season in South Carolina because Hurricane Ian delayed delivery of flu vaccines. The pandemic has made RSV and the flu present in new ways and at odd times of the year , said William Schaffner, medical director for the nonprofit National Foundation for Infectious Diseases and a professor of infectious diseases at that Vanderbilt University School of Medicine. “It’s just that children were sheltered from it,” he said. Unlike with measles or mumps, people can get RSV multiple times during their lives. Once the virus has run its course, Schaffner said, people usually have more immunity for a year or two. But that becomes an issue, with all the different respiratory illnesses flourishing during winter. “There are some of us who are concerned we may have a tridemic” of RSV converging with covid-19 and the flu, Schaffner said.

Is there an RSV vaccine?

There is no government-approved RSV vaccine, Gounder said. Researchers have tried for half a century to develop a vaccine or treatment for RSV, she said, and they’re closer than ever . “We have may have one within five years or so available to young kids under the age of 5,” Gounder said. She said there are two expected methods to vaccinate children against RSV: a direct injection and vaccinating the person carrying the child. That’s especially exciting to the medical community, because few vaccinations are given to children younger than 6 months, Gounder said. Children are born with antibodies provided by their mother, and research shows that vaccinations given during that time may not be as effective as ones administered later. There may not be a cure, but there is a preventive RSV drug. Palivizumab, sold under the name Synagis, is a monoclonal antibody treatment given to at-risk infants before RSV season, Schaffner said. But, as with the coronavirus, doctors prefer an active vaccination that gives a body what it needs to create its own protection instead of a monoclonal antibody treatment. Think of it as teaching a body to fish versus just giving it fish.

What do I do if my child has RSV?

Aside from the cold-like symptoms, Gounder said there are other signs of a serious RSV case — children may be more irritable, not feed as well, seem lethargic or cough so much they can’t breathe. Another sign of a severe RSV case is if a child is “pulling,” which Gounder characterized as a struggle to breathe, tugging skin around the ribs or clavicle. Most of the focus has been on children getting RSV and filling up pediatric units, but the elderly are also susceptible to the virus . Expert advice remains the same: Wash your hands, clean surfaces and seek medical care if someone isn’t doing well.

Hospitals are worried about child RSV this year. Here’s what to know.

By Ben Brasch

Updated October 23, 2022 at 10:04 p.m. EDT|Published October 21, 2022 at 5:32 p.m. EDT

6 min

Staffs at U.S. hospitals — especially in pediatric wings — have seen a sharp rise in the number of patients suffering from respiratory syncytial virus, or RSV, this fall.

The virus has come earlier and hit harder than in most years, according to experts. Infectious-disease specialists worry about what will happen to the health-care system if RSV, influenza and covid-19 peak at the same time — a “tridemic,” as one expert called it.

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RSV primarily affects children, but a spike would tax all parts of the medical system. As in the coronavirus pandemic’s worst days, elective surgeries could be paused again, doctors’ offices could be flooded with calls, people could fill emergency rooms.

Here’s what RSV is and why it has become such a problem on such a large scale: