CDC prepares for possible RSV, Covid and flu winter ‘tripledemic’

Even as the nation is faced with blistering heat waves this summer, Dr. Mandy Cohen, director of the Centers for Disease Control and Prevention, is already thinking ahead to cold and flu season this winter.

“We’re going to have three bugs out there, three viruses: Covid, of course, flu and RSV,” Cohen said in an interview. “We need to make sure the American people understand all three and what they can do to protect themselves.”

Spread of all three respiratory viruses is currently low, but the CDC has begun to detect slight increases in positive Covid tests and Covid-related emergency department visits. And the decline in Covid hospitalizations has stalled.

Omicron XBB subvariants remain the most prevalent forms of Covid, though on Wednesday, the World Health Organization identified a new XBB version, the EG.5, as rising in prevalence around the world and in the U.S.

It’s unclear what — if anything — the emergence of EG.5 means. The WHO noted there’s no evidence that it causes more severe illness. Cohen said that so far, the virus remains susceptible to Covid shots. 

For the first time this fall, the U.S. will have access to vaccines for another expected virus: respiratory syncytial virus, or RSV. Those shots, along with a new monoclonal antibody injection for babies and a third vaccine up for approval, have the potential to drastically reduce cases of the virus that typically hits infants and older adults hardest, experts say.

An unexpectedly severe surge of RSV infections in late 2022 overwhelmed children’s hospitals with babies and young kids whose immune systems hadn’t been exposed to the virus during lockdown. 

On July 17, the Food and Drug Administration approved a monoclonal antibody injection to help prevent RSV for children up to age 2. Unlike a vaccine that prompts the body to make its own antibodies, the injection works by delivering antibodies against RSV directly into the bloodstream.

And as soon as next month, the FDA could approve the first RSV vaccine for pregnant women, who would then transfer those antibodies to their babies. 

Two other RSV vaccines, for adults ages 60 and over, were approved earlier this year.

Timing Covid, flu and RSV vaccines

This means that many Americans will be urged to get three different vaccinations this fall: Covid, RSV and the annual flu shot. But that will be a challenge for the health care system, said Dr. William Schaffner, an infectious diseases expert and professor of preventive medicine at Vanderbilt University Medical Center. 

“We’re going to have to learn how to deliver those vaccines in a way that’s effective in actually reaching the population at a time when there’s already vaccine fatigue,” he said.

Some may be wary of getting three shots at once, a concern Schaffner echoed. Combining flu and Covid vaccines doesn’t appear to reduce the effectiveness of either shot, but Schaffner said that there is limited data suggesting that adding the RSV shot to the mix lessens the response. 

“I think most of us are going to recommend it’s OK to get flu and Covid vaccines together, but wait a bit until you get the RSV” shot, he said.

Last year, flu season began unusually early — in October — and peaked quickly. There is no indication yet what the U.S. will face this year.

“Right now, they’re having a pretty standard flu season in the Southern Hemisphere,” Cohen said. “But it’s still early days.”