H3N2 (IMAGE) University of Wisconsin-Madison Caption An image of H3N2 viruses. H3N2 is a strain of influenza that commonly makes people sick during flu season and can cause more severe disease than other strains. Credit Yoshihiro Kawaoka, UW-Madison Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.