Interim Estimates of 2017–18 Seasonal Influenza Vaccine Effectiveness — United States, February 2018

Abstract

© 2018, Department of Health and Human Services. All rights reserved. What is already known about this topic? Effectiveness of seasonal influenza vaccine can vary by season and has generally been higher against influenza A(H1N1)pdm09 and B viruses than against A(H3N2) viruses. What is added by this report? So far this season, influenza A(H3N2) viruses have predominated, but other influenza viruses are also circulating. Based on data from 4,562 children and adults with acute respiratory illness enrolled during November 2, 2017-February 3, 2018, at five study sites with outpatient medical facilities in the United States, the overall estimated effectiveness of the 2017-18 seasonal influenza vaccine for preventing medically attended, laboratory-confirmed influenza virus infection was 36%. What are the implications for public health practice? CDC continues to monitor influenza vaccine effectiveness. Influenza vaccination is still recommended; vaccination reduces the risk for influenza illnesses and serious complications. Treatment with influenza antiviral medications, where appropriate, is especially important this season.