U.S. Flu Season Report
NEW YORK (AP) — As the flu season in the U.S. draws to a close, health officials report that the flu vaccine’s effectiveness has been notably low, marking one of the poorest rates in over ten years.
A new strain that was prevalent during early winter did not match well with this season’s vaccine, resulting in a significant early wave of flu cases.
On Friday, the Centers for Disease Control and Prevention released data indicating a continued decrease in doctor visits and hospitalizations due to flu symptoms, with 16 states, primarily in a corridor from Colorado to Virginia, still reporting high levels of flu activity.
“The winter respiratory virus season is gradually coming to an end, and, honestly, we’re all quite thankful for that,” commented Dr. William Schaffner, a vaccine expert from Vanderbilt University.
This year’s flu vaccines were found to be about 25% to 30% effective in preventing adults from becoming ill enough to seek medical attention, according to a recent CDC report. For children, vaccination led to a 40% reduced likelihood of needing treatment.
Generally, health officials are satisfied when vaccines reach 40% to 60% effectiveness. Based on historical CDC data, this season ranks among the lowest in vaccine efficacy over the past two decades.
Flu cases surged dramatically in late December, with some regions experiencing particularly severe outbreaks. In fact, health officials from New York City described it as the most intense flu season in the last 20 years.
The relatively low vaccination rates were a contributing factor, yet experts also pointed fingers at the new strain responsible for the majority of infections.
This recently identified strain, a subtype of the A H3N2 virus known as subclade K, appeared to spread more easily, although it didn’t necessarily result in more severe illness.
The vaccine developed for this season targeted a different H3N2 variant, and experts believe this mismatch largely explains the vaccine’s lack of effectiveness, according to Schaffner.
CDC estimates indicate that there have been at least 27 million flu illnesses, 350,000 hospitalizations, and 22,000 deaths this season. For comparison, at this time last year, there were estimates of at least 40 million illnesses and 520,000 hospitalizations, but similar death counts.
This season has seen at least 101 child fatalities, with approximately 85% of those children not fully vaccinated against the flu.
While the flu vaccine may not prevent everyone from getting sick, it can significantly reduce the severity of the illness and associated deaths. Thus, Schaffner emphasizes the continued importance of flu vaccinations.
CDC data suggests that adult vaccination rates have increased slightly to 46.5% this season, following a notably harsh previous year that witnessed a record number of child deaths.
As of the end of last month, about 48% of U.S. children had received the flu vaccine, remaining steady compared to last year, but down from 52% in early 2024, according to CDC data.
Since 2010, the recommendation has been for annual flu vaccinations for Americans aged six months and older. However, in January, the Trump administration retracted its broad recommendation for flu shots for all children, leaving the decision up to parents and family physicians.
As plans for next winter’s flu season are already in progress, last month the World Health Organization announced its recommendations for the virus strains to include in the vaccines for the 2026-27 northern hemisphere flu season, emphasizing the need to target subclade K. Recently, a U.S. Food and Drug Administration advisory committee endorsed these WHO recommendations.
