Flu Shots Are Moderately Effective This Season, CDC Says

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March 1, 2024 -- The vaccines for this flu season are 41% to 44% effective in preventing flu-related hospitalization in adults and 52% to 61% effective for children, according to estimates in the CDC’s Morbidity and Mortality Weekly Report issued Thursday.

Officials with the federal health agency said that the findings from their report show that the flu shot for the 2023 to 2024 season is effective at reducing the risk of flu-related doctor's visits and hospitalizations. Overall, this season's flu shot effectiveness is about the same as previous years. 

"We're right in the range that we typically see when the vaccine is a good match with the viruses that are circulating. Good vaccine effectiveness, and it's working consistent with past years," said Sascha Ellington, PhD, head of the CDC's influenza prevention and control team, according to CBS News

The estimates on vaccine effectiveness are based on ongoing CDC studies that draw on records from immunization registries, clinics, urgent care services, emergency rooms, hospitals, and health insurance claims. 

Flu vaccines are tweaked each year to work against what health authorities predict will be the dominant flu strains. This flu season, the vaccines have been designed to work against two subtypes from influenza A and two from influenza B.

An FDA committee is scheduled to vote Tuesdayon which vaccines would be used next flu season, CBS News reported. 

FDA and World Health Organization committees have urged removal of vaccine components that target the influenza B Yamagata subtype, which disappeared during the COVID pandemic, CBS News said. If that idea is approved, the vaccines would go from quadrivalent to trivalent next flu season.

The CDC said recently that flu levels remain elevated nationally, with increases in flu activity in the Middle Atlantic, the Midwest, and the Central States.

The CDC’s Advisory Committee on Immunization Practices recommends everyone over 6 months receive an annual flu shot.