A wave of RSV, especially dangerous for children, is spreading across the United States

A wave of the highly contagious respiratory syncytial virus is sweeping across the United States — sending large numbers of infants and toddlers to the hospital, the latest data shows.

The RSV outbreak comes as the country heads into the fall and winter widespread respiratory virus season, which is also marked by an increase in illnesses such as COVID-19 and the flu. But RSV, the leading cause of pediatric hospitalizations nationwide, poses a particular risk to young children, a major reason health experts recommend that pregnant women get vaccinated closer to their due date or vaccinate their newborns.

“This is the perfect time to get your vaccine for RSV if you’ve never gotten one,” the Los Angeles County Department of Public Health said in a statement to The Times.

RSV can be spread by coughing or sneezing but also by touching a contaminated surface, such as a doorknob, and then touching your face before washing your hands, health officials warn.

For the week ending Oct. 11, about 1.2% of emergency room visits nationwide among children younger than 1.2 were due to RSV — up from 0.4% a month earlier, according to data posted by PopHIVE, a project led by the Yale School of Public Health.

“The RSV wave is starting to take hold,” wrote epidemiologists Caitlin Gitellina and Hannah Tutti on the Your Local Epidemiologist blog.

According to the US Centers for Disease Control and Prevention, RSV can be dangerous for children, the elderly and people with certain medical conditions. RSV can cause pneumonia, as well as a severe inflammation of the small airways of the lungs, known as bronchiolitis, the California Department of Public Health said.

“The issue with children is that their airways are so small that when inflammation develops in the airways, it’s very difficult to breathe,” said Dr. Peter Chen Hong, an infectious disease specialist at UC San Francisco. “So they come in with a cough … and that’s why they get in trouble.”

Nationally, RSV kills up to 300 children under the age of 5 a year, and can send up to 80,000 to the hospital. According to the CDC, among seniors age 65 and older, the virus can cause up to 10,000 deaths and up to 160,000 hospitalizations in a typical year.

“I think it was kind of unclear, especially because until recently … people wouldn’t get tested — we couldn’t test for RSV until the age of molecular diagnostics,” Chen Hong said. “So it was kind of an invisible disease.”

RSV is “the bronze medalist type of respiratory virus, with COVID and influenza No. 1 and No. 2, it’s killing it, and RSV is No. 3 for older adults,” he added. In general, RSV is the first to emerge in the fall and winter virus season, followed by the flu then COVID, Chen Hong said.

Before vaccines were available, between 2% and 3% of young children were hospitalized for RSV each year, according to the CDC. Most children hospitalized for severe respiratory illness caused by RSV were previously healthy, according to a study published in the journal Pediatrics.

They may need oxygen or intravenous fluids or even be put on a ventilator to help them breathe, according to the CDC.

As with influenza and COVID-19, there are no antiviral medications available to treat RSV once infection has occurred.

For now, the combined respiratory disease activity from RSV, flu and COVID-19 is considered “very low” in California, state health officials said.

But “we’re starting the respiratory virus season,” the LA County Department of Public Health said.

Health officials in Northern California’s most populous Santa Clara County are already reporting “moderate” levels of RSV in wastewater from San Jose, Palo Alto and Sunnyvale.

Now is the time to get vaccinated if you haven’t already — “especially before respiratory virus activity is likely to increase later,” said Dr. Regina Chinseo Kwang, Orange County health officer.

The RSV vaccine is recommended for pregnant women between 32 and 36 weeks of gestational age – about one to two months before their expected delivery date – as well as those aged 75 to 74 and those aged 50 to 74 with underlying medical conditions such as diabetes, cancer, kidney disease, a weakened immune system or heart disease, lung disease. The vaccine is also recommended for people who live in a nursing home or long-term care facility.

If a pregnant woman is not vaccinated against RSV, authorities recommend that her baby be vaccinated.

RSV vaccines are relatively new, introduced in 2023. There are now three brands – Pfizer’s Abrysvo and GSK’s Arexvy licensed in May 2023, and Moderna’s mResvia in June 2024. All three can be used for older adults, but only the Pfizer vaccine is available for women.

Children were also able to get vaccinated earlier that year with monoclonal antibodies, which aren’t technically vaccines but work the same in this case.

Older adults who have already received the RSV vaccine usually do not need to receive another vaccine.

The arrival of these vaccines specifically followed the 2022-23 respiratory virus season when California was hit by a hospital-strained “tripledemic” of RSV, flu and COVID.

Unlike the RSV shots, the flu and COVID vaccines are generally recommended before the fall and winter viral respiratory season. According to the California Department of Public Health, older adults, ages 65 and older, can get the COVID vaccine every six months.

People can get RSV, flu and COVID vaccines during the same visit to a health care provider, Chensiu Kwang said.

“Getting all eligible vaccines at once is considered a best practice, as it helps avoid missed opportunities due to scheduling challenges,” she said.

Studies have shown that RSV vaccines are effective.

During last year’s respiratory virus season, there was a significant decrease in RSV hospitalization rates for children, the data show. Data also show that the RSV vaccine was effective in preventing symptomatic disease in older adults.

Chen Hong said he recommends “everyone should get it” if they’re 75 or older, and those between the ages of 50 and 74 have heart or lung disease or are very immune-compromised, “I think the juice is worth a sip.”

An annual routine flu vaccine is recommended for everyone at least 6 months old.

As for COVID, a vaccine can be given to anyone who wants one. The California Department of Public Health specifically advises all children age 65 and older, infants 6 months to 23 months of age, children and adolescents who have never been vaccinated, and people with certain health risk factors and those in close contact with them.

The California Department of Public Health also recommends that pregnant women receive the COVID vaccine.

After concerns earlier this season about how difficult it would be to get the COVID vaccine, pharmacists and California health officials now say the shots are relatively easy to secure.

The controversy erupted in late summer amid tumultuous guidance from agencies overseen by Health and Human Services Secretary Robert F. Kennedy Jr., who has decriminalized vaccines.

There was a period when the Food and Drug Administration begrudgingly approved Covid-19 vaccines only for people aged 65 and over and for younger people with underlying health conditions. The CDC’s unprecedented delay in issuing its recommendations has had the effect of putting off vaccinations for many.

In some states, that meant people were being turned away from getting a COVID vaccine at their local pharmacy, including seniors, even as a surge emerged in late summer. And at one point, the CDC’s powerful Advisory Committee on Immunization Practices almost recommended that the COVID vaccine be available only by prescription.

On October 6, CDC Acting Director Jim O’Neill formally lifted the agency’s recommendation that adults under the age of 65 receive the new COVID-19 vaccine, saying it should be based on “individualized decision-making” in consultation with health professionals.

Now, “patients can go to the pharmacy” and have a conversation with a professional about whether to get a COVID-19 vaccine, Alison Hill, director of professional affairs for the American Pharmacists Assn., said during a recent webinar.

California also recently clarified state law to ensure that pharmacists can independently administer the COVID vaccine, according to Dr. Erica Penn, director of the Department of Public Health.