How Effective Is the Flu Vaccine at Preventing Flu?
Flu vaccine effectiveness varies from year to year, but it typically prevents 30 to 60% of flu cases, with stronger protection generally seen in children. Confirmed data from the completed 2025/26 season shows the vaccine provided meaningful protection even against a newly evolved flu strain, which is a reassuring sign as this year's vaccination campaign gets underway. How Effective Was Last Season's Flu Vaccine? Last season's flu vaccine (2025/26) was confirmed to be 67.9% effective at preventing hospital attendance in children aged 2 to 17, 21.7% effective in adults aged 18 to 64, and 29.1% effective in adults aged 65 and over. These final figures come from UKHSA's annual epidemiological report , covering a season in which flu activity was driven by a drifted strain of influenza A known as subclade K. These results sit within the typical range for flu vaccine effectiveness and show the vaccine did its job well, despite the virus having evolved slightly since the va...