This year's (2024-2025) flu vaccine effectiveness is reported with mixed and somewhat concerning findings. A major study from the Cleveland Clinic found that the vaccine did not effectively prevent influenza infection in adults during this season, even showing a negative effectiveness (-26.9%), meaning vaccinated individuals had a higher rate of infection than unvaccinated ones in this large group of employees studied. However, this study was a pre-print and not peer-reviewed yet, so caution is advised in interpretation. Other data from Germany indicates moderate vaccine effectiveness around 31% against any influenza in primary care settings, with higher effectiveness (69%) against hospitalization. This suggests some protection especially against severe outcomes. Typically, the flu vaccine in recent years shows effectiveness ranging from about 40-60%, and even a lower effectiveness can still reduce severe illness, hospitalization, and death risks.
In summary, this year's flu shot appears less effective than usual at preventing infection overall, with some benefit still likely especially against severe disease, but effectiveness varies by population, setting, and circulating strains. Getting vaccinated remains important as part of broader flu prevention strategies.