This report describes the investigation of two cases of febrile respiratory illness caused by swine influenza A (H3N2) viruses identified on the 19th and the 26th August 2011 in two different states in the US (Indiana and Pennsylvania).

This Public Health Development is an update of an earlier Public Health Development published by ECDC on 28th October 2011 (1).

A report in the US Centers for Disease Control and Prevention (CDC) MMWR this week describes the investigation of mild respiratory illness among swine and people at a county fair  in Indiana, USA between 8 and 14 July 2012. This is an important report as it is very clearly documents simultaneous detection of H3N2v influenza viruses in humans and swine in close contact.

​In August 2014, the US Centers for Disease Control and Prevention (CDC) reported two laboratory-confirmed human infections with a A(H3N2) variant influenza virus of swine origin A(H3N2)v in Ohio, USA.

Since July 2011, 155 cases of the variant influenza A(H3N2) virus (A(H3N2)v) have been detected in the US: Hawaii (1), Indiana (113), Iowa (3), Maine (2), Ohio (30), Pennsylvania (3), Utah (1), and West Virginia (2). Most cases reported in Indiana and Ohio are recent cases. No human to human transmission has been determined among these recent cases.