US flu activity dips slightly as health officials warn severe season has not peaked

U.S. flu activity showed a modest decline last week in two key measures — medical office visits for flu-like illness and the count of states reporting high activity — but federal health officials said the severe season has not peaked and warned that more suffering lies ahead.

The U.S. Centers for Disease Control and Prevention estimated at least 15 million flu illnesses, 180,000 hospitalizations, and 7,400 deaths since the season began, including the deaths of at least 17 children. Even as some indicators eased, flu-related deaths and hospitalizations continued to rise during the same week.

The dominant circulating strain — influenza A H3N2, historically responsible for the most severe outcomes in older adults — is spreading in a form that differs from the virus targeted by this year’s flu shots, raising concern that the season’s severity could persist. The outlook is further complicated by a federal policy change announced Monday removing flu vaccination from the routine childhood immunization schedule.

Subclade K and the vaccine mismatch

More than 91 percent of H3N2 infections analyzed so far this season were identified as the subclade K variant, a form of the virus that differs from the strain included in this year’s flu shots.

Forty-four states reported high flu activity last week, down slightly from the prior week. Flu-related deaths and hospitalizations, however, rose during the same period.

“This is going to be a long, hard flu season,” New York State Health Commissioner Dr. James McDonald said in a statement Friday.

A season already tracking above last winter

The current season is on track to surpass last winter’s epidemic, which was itself one of the harshest in recent history. Last season recorded the highest overall flu hospitalization rate in the United States since the H1N1 pandemic 15 years ago. Child flu deaths reached 289, the worst figure recorded for any U.S. flu season this century, including the 2009–2010 H1N1 swine flu pandemic.

Vaccine policy shift draws criticism

Federal health officials announced Monday that they will no longer recommend flu vaccination as a routine measure for U.S. children, describing it as a decision for parents and patients to make with their doctors. For years, federal agencies and doctors’ groups had recommended annual influenza vaccination for everyone 6 months of age and older. Experts say the shots, while not preventing all infections, can reduce the likelihood that an infection becomes severe.

Michele Slafkosky, executive director of Families Fighting Flu, said in a statement: “I can’t begin to express how concerned we are about the future health of the children in this country, who already have been unnecessarily dying from the flu — a vaccine preventable disease.”

“Now, with added confusion for parents and health care providers about childhood vaccines, I fear that flu seasons to come could be even more deadly for our youngest and most vulnerable,” she said.

Seasonal uncertainty and co-circulating viruses

Flu season data can be difficult to interpret in the weeks around major holidays. School closures and travel affect both transmission patterns and the likelihood that patients seek care. Some seasons also show a secondary surge after an initial decline, adding uncertainty about whether the current dip signals a true turning point.

Flu is one of several respiratory viruses circulating this winter. Hospitalizations from COVID-19 and respiratory syncytial virus have also been rising in recent weeks, though both were diagnosed far less frequently than influenza during the same period, according to federal data.