Interim Estimate Suggests Flu Shot Not Effective in 2021-2022 Season

THURSDAY, March 10, 2022 (HealthDay News) -- During the 2021-2022 season, influenza vaccination did not reduce the risk for outpatient medically attended illness with influenza A(H3N2) viruses that have predominated this season, according to research published in the March 11 issue of the U.S. Centers for Disease Control and Prevention Morbidity and Mortality Weekly Report.

Noting that most influenza viruses detected this season have been A(H3N2), Jessie R. Chung, M.P.H., from the CDC in Atlanta, and colleagues produced an interim report using data from 3,636 children and adults with acute respiratory infection during Oct. 4, 2021, to Feb. 12, 2022.

The researchers found that vaccine effectiveness against medically attended outpatient acute respiratory infection associated with influenza A(H3N2) virus was 16 percent overall, which was not statistically significant.

"Physicians should not wait for confirmatory influenza laboratory testing, and the decision to use antiviral medication should not be influenced by patient influenza vaccination status," the authors write. "Clinicians should be aware that influenza activity might continue or increase, and influenza should be considered as a possible diagnosis in all patients with acute respiratory infection."

Several authors disclosed financial ties to the pharmaceutical industry.

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