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News & features archive, 2011

Standardization of terminology for the variant A(H3N2) virus recently infecting humans

Joint announcement of FAO, OIE and WHO
23 December 2011 - FAO, OIE and WHO continue working closely together to address influenza issues related to public health and animal health.

Since July 2011, twelve human cases of infection with a variant influenza A(H3N2) virus have been detected in the United States. To date, no report has been received from elsewhere in the world. This virus has different virological characteristics from current circulating seasonal influenza viruses in humans, and has a new gene constellation: 7 genes from the triple reassortant A(H3N2) viruses known to have been circulating in pigs in the North America and the M gene from an A(H1N1)pdm09 virus, a seasonal virus currently circulating in humans.

In order to improve communications and avoid confusion, FAO, OIE and WHO have established a working group of experts to standardize the terminology for variant influenza viruses. The joint recommendation for the above mentioned A(H3N2) virus is: A(H3N2)v , where “v” stands for “variant”.

An example of use of the terminology:

  • Sporadic human cases of infection with a variant influenza A(H3N2) virus A(H3N2)v have been reported in the USA. The A(H3N2)v virus is different from seasonal viruses currently circulating in humans.

For more information, please contact FAO at [email protected], OIE at [email protected] and WHO at [email protected].

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