Reviewing the 2025-26 Flu Season: Vaccine Effectiveness, Impact, and Future Preparations
As the flu season in the United States comes to a close, health officials have reported that this year's flu vaccine had low effectiveness due to a new strain that was not well matched to the vaccine. The Centers for Disease Control and Prevention (CDC) noted a decrease in flu-related doctor's visits and hospitalizations in the past week, with only 16 states still reporting high flu activity.
The flu vaccine this season was only 25% to 30% effective in preventing adults from getting sick enough to seek medical treatment, while children who were vaccinated had a 40% lower likelihood of needing medical care. This effectiveness rate is lower than what is typically expected for flu vaccines, making it one of the least effective in recent years.
The surge of flu infections in late December was particularly severe in some regions, with New York City experiencing its most intense flu season in two decades. The new strain of flu virus, A H3N2 subclade K, was responsible for most infections and was not effectively targeted by the vaccine, leading to the lower effectiveness rate.
Despite the lower effectiveness of this year's flu vaccine, health experts emphasize the importance of getting vaccinated as it can still prevent severe illness and death. The CDC estimates that there have been millions of flu-related illnesses, hospitalizations, and deaths this season, with a significant number of children affected.
While adult vaccination rates have slightly increased this season, children's vaccination rates have remained steady compared to previous years. The government's recommendation for annual flu vaccinations for all Americans over 6 months old has been in place since 2010, but the Trump administration recently shifted the responsibility to parents and doctors to decide on flu shots for children.
Looking ahead to the next flu season, the World Health Organization has recommended virus strains to be included in the 2026-27 flu vaccines, with a focus on addressing subclade K. The U.S. Food and Drug Administration advisory committee has endorsed these recommendations, signaling preparations for the upcoming flu season.
In conclusion, this year's flu season in the U.S. was marked by a less effective vaccine due to a new strain of flu virus. Despite the challenges, health officials stress the importance of getting vaccinated to reduce the risk of severe illness and death from the flu. As preparations begin for the next flu season, efforts are underway to address the specific virus strains and improve vaccine effectiveness for the future.