CDC: Interim Guidance on Case Definitions to be Used For Investigations of Influenza A (H3N2)v Virus Cases

[This will be filed on the right side-bar under H3N2v Information List for future reference]

Posted on July 3, 2013

This document provides updated interim guidance for state and local health departments conducting investigations of infections with influenza A (H3N2) variant (H3N2v) viruses. Influenza viruses that typically infect swine are referred to as “variant” when they infect humans. The following definitions are for the purpose of investigations of confirmed cases and cases of influenza A (H3N2)v virus infection under investigation. CDC is requesting notification of all confirmed cases of influenza A (H3N2)v virus infection within 24 hours of identification. When possible, state health departments are encouraged to investigate all potential cases of influenza A (H3N2)v virus infection further to determine case status.

Case Definitions for Infection with Influenza A (H3N2)v Virus

Confirmed: Influenza A (H3N2)v virus infection in a patient with laboratory confirmation by:

• Reverse-transcription polymerase chain reaction (RT-PCR) testing or genetic sequencing results positive for influenza A (H3N2)v virus at the CDC Influenza Division Laboratory

OR

• RT-PCR testing results at a public health laboratory consistent with influenza A (H3N2)v virus using a CDC-approved assay (for example, InfA, H3, and pdmInfA positive results, and H1 and pdmH1 negative results using the CDC Flu rRT-PCR Dx Panel)¹. Please see Interim Guidance on Specimen Collection, Processing, and Testing for Patients with Suspect Influenza A (H3N2)v Virus Infection for additional guidance on testing for H3N2v viruses.

Continued:  http://www.cdc.gov/flu/swineflu/case-definitions.htm