As the U.S. flu season winds down, health officials said the flu vaccine did not work very well—showing one of the lowest effectiveness rates in more than a decade—while CDC data Friday pointed to continued improvement in flu-related visits.
The Centers for Disease Control and Prevention posted surveillance data showing a continued decline in doctor’s office and hospital visits for flu symptoms through last week. The number of states reporting high flu activity dropped to 16, with many of them in a belt stretching from Colorado to Virginia.
“The winter respiratory virus season is slowly coming to a close, and we’re all very grateful for that,” said Dr. William Schaffner, a Vanderbilt University vaccine expert.
Federal officials attributed the weak performance largely to strain mismatch. They said a new flu strain that dominated early winter was not well matched to the vaccine, contributing to an intense early onslaught of flu.
This season’s vaccines were about 25% to 30% effective in preventing adults from getting sick enough to seek care at a doctor’s office, clinic or hospital, according to a CDC report this week. For children who were vaccinated, CDC reported they were about 40% less likely to receive treatment at a doctor’s office or hospital.
Officials generally described 40% to 60% effectiveness as a range that would satisfy expectations for flu vaccines, and they said the current season’s rate was among the lowest seen in the last two decades. CDC scientists estimated there have been at least 27 million illnesses, 350,000 hospitalizations and 22,000 deaths from flu so far this season. At the same point last year, the estimates were at least 40 million illnesses and 520,000 hospitalizations, with about the same number of deaths.
CDC data also showed the season was especially severe for children. At least 101 children have died so far this season, and among children whose vaccination status was known, about 85% were not fully vaccinated against flu.
Schaffner said the vaccine may not protect everyone from getting sick, but it can prevent people from becoming severely ill and dying, adding that getting a flu shot remains worthwhile.
The CDC data also showed adult vaccination rates were up slightly this season, to 46.5% after last year’s unusually bad season. About 48% of U.S. children were vaccinated against flu around the end of last month, roughly the same as last year but down from 52% vaccinated at this point in 2024, CDC data showed.
The timing and strain match matter, Schaffner said. He pointed to a new H3N2 version—subclade K—that seemed to spread more easily, while not necessarily causing more severe illness. He said the vaccine available for the season had been built to address a different version of H3N2, and the spread of subclade K was a likely explanation for why the vaccine was less effective.
Flu infections surged in late December and were especially intense in some parts of the country, the AP report said. New York City health officials called it the most intense season in 20 years.
Work is already underway to select strains for next winter’s flu vaccines. The World Health Organization announced recommendations for which virus strains to address in 2026-27 northern hemisphere flu vaccines, and it said vaccines should be built to handle subclade K. This week, a U.S. Food and Drug Administration advisory committee endorsed the WHO recommendations.
CC0 — This article is available under the Creative Commons CC0 1.0 Universal license. AI disclosure: generated by Main Street Independent’s News Article Generator framework.