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Flu, RSV and Covid may have peaked. But the threat isn't over.

It's impossible to predict what happens next, infectious disease doctors say. Young children, in particular, are still at risk for respiratory viruses.
Emergency personnel load an ambulance in front of Mount Sinai Hospital in New York on Jan. 12, 2023.
Emergency personnel load an ambulance in front of Mount Sinai Hospital in New York on Jan. 12. Seth Wenig / AP

Emergency room visits related to three of the most disruptive viruses — the flu, respiratory syncytial virus and Covid — are falling nationwide.

But does that mean the feared "tripledemic" is over? Hardly, experts say. Viruses are notoriously hard to forecast.

"We've all learned over the past couple years, when you try to predict Covid, you'll get slapped in the face," said Dr. Katie Passaretti, vice president and enterprise chief epidemiologist for Atrium Health in Charlotte, North Carolina.

Still, hospital emergency room visits for the biggest viral threats began to fall in December, with the decline continuing this month. This is especially true for flu.

Children got double viral infections

Trying to guess what flu will do between now and the end of flu season is "hazardous," warned Dr. William Schaffner, an infectious disease expert at Vanderbilt University Medical Center in Nashville, Tennessee. "It is impossible to predict what will happen next."

As most families already know, flu and other viruses have been especially hard on children compared with adults, according to a study published Thursday by the Centers for Disease Control and Prevention.

Schaffner is a co-author, along with Dr. Christine Thomas, an epidemic intelligence service officer at the CDC who works with the Tennessee Department of Health.

"We were really curious to see what this year would look like" following several years of almost no flu, Thomas said.

Their report focused on 4,626 people in Tennessee who got a flu test in mid-November. Flu, researchers found, spiked early and hit children the hardest. Children were twice as likely as adults to test positive, and they tended to be sicker, especially if they were infected with several viruses at once, such as the common cold on top of flu.

A separate study from earlier this week found that children hospitalized with Covid had more severe symptoms if they also had another virus.

Children ages 5 and younger are at risk because their tiny immune systems may not have been exposed to many common viruses during the pandemic.

"If you get a double infection, it tends to make you a tad sicker, you're apt to stay in the hospital a little longer," Schaffner said.

Flu hospitalizations for very young children in Tennessee have already reached peak levels seen in other bad flu seasons, at 12.6 per 100,000, the new study found. This is similar to what's been reported nationally.

But this season is not over. While most flu cases so far have been A strains of the virus, B strains tend to pop up by spring.

"I do suspect that we will have more bumps in the road this respiratory viral season," Passaretti said. She was not involved with the new study.

Few who tested for flu in the Tennessee report were vaccinated. Just 23% of children and 34% of adults had received their flu shots.

And having influenza A doesn't offer immunity to the B strain. That is, a person can get the flu twice in a single season.

"That's a reason to still get vaccinated," Schaffner said. "Flu probably won't go away completely until we get into the early summer."

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