Interim Estimates of 2021-22 Seasonal Influenza Vaccine Effectiveness - United States, February 2022

What is already known about this topic? Annual vaccination against seasonal influenza is recommended for all persons in the United States aged >= 6 months. Effectiveness of seasonal influenza vaccine varies by influenza season. What is added by this report? Based on data from 3,636 children, adolescents, and adults with acute respiratory infection during October 4, 2021-February 12, 2022, seasonal influenza vaccination did not reduce the risk for outpatient respiratory illness caused by influenza A(H3N2) viruses that have predominated so far this season. What are the implications for public health practice? CDC recommends influenza vaccination for as long as influenza viruses are circulating. Vaccination can prevent serious influenza-related complications caused by viruses that might circulate later in the season, including 2009 pandemic A(H1N1) and influenza B viruses.

Automated summary

Seasonal influenza vaccination did not reduce the risk for outpatient respiratory illness caused by H3N2 viruses in the current season, but CDC still recommends vaccination as long as influenza viruses are circulating to prevent serious complications caused by other viruses that might circulate later in the season.