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Flu activity is increasing sharply across the US

<i>Marco Bello/Reuters via CNN Newsource</i><br/>

By CNN Newsource

Published December 30, 2025 11:42 am

By Deidre McPhillips, CNN

(CNN) — Most US states are experiencing high or very high flu activity, and levels continue to increase nationwide.

“Flu season is just getting started, so I think it’s really hard to say exactly what it’s going to look like,” Dr. Michael Osterholm, director of the Center for Infectious Disease Research and Policy at the University of Minnesota, told CNN on Tuesday. “What we’re seeing right now is a very rapid escalation of cases.”

The US Centers for Disease Control and Prevention estimates that there have been at least 7,500,000 illnesses, 81,000 hospitalizations, and 3,100 deaths from flu so far this season, according to an update published by the agency on Tuesday with data through December 20. At least eight children have died from flu so far this season.

Among the states with the highest levels of flu activity are Colorado, Louisiana, New Jersey, New York and South Carolina, according to the CDC.

Trends are increasing across key surveillance metrics: laboratory testing, outpatient health care visits, hospitalizations and mortality are all higher than they were a week ago.

One surveillance system shows that flu hospitalizations doubled over the past week; more than 19,000 people were admitted to the hospital with flu during the most recent week, up from about 9,900 hospital admissions the week before.

The CDC says that “severity indicators remain low at this time, but influenza activity is expected to continue for several weeks.”

Influenza A(H3N2) viruses are the most commonly reported, and additional genetic testing suggests that a new flu variant — called subclade K — that caused early and busy flu seasons in other part of the world appears to be driving the vast majority of cases in the US.

The CDC recommends that everyone age 6 months and older get a flu vaccine each season, but vaccination rates have been decreasing in recent years. Only about 130 million flu vaccines have been distributed this season, CDC data shows, 13 million fewer doses than by this time last year. Additional data suggests that only about 17% of children and 23% of adults had gotten their seasonal flu vaccine by the end of November.

Osterholm encourages people who haven’t yet been vaccinated against flu to act quickly as the virus is “wiping through” the country.

“It’s not too late to get your flu shot,” he said. “It doesn’t guarantee you won’t get flu. It doesn’t guarantee that you still won’t get sick, but it surely is a big improvement on what the otherwise outcome could be of either being seriously ill or dying.”