Evolution of the influenza A(H5) haemagglutinin: WHO/OIE/FAO H5 Working Group reports a new clade designated 2.3.4.4

Overview

In 2014, detections of highly pathogenic avian influenza A(H5N8) in East Asia and Europe, A(H5N8) and A(H5N2) in North America, and A(H5N6) in East and Southeast Asia, prompted the WHO/OIE/FAO H5 Evolution Working Group to review and update the H5 haemagglutinin (HA) clade nomenclature, last revised based on sequence data available prior to December 2012, for H5N1, H5N2, H5N5, H5N6, and H5N8 subtype viruses clustering in this HA group. The virology, animal and public health communities are encouraged to adopt the clade designation 2.3.4.4 for these H5 HAs and discontinue use of the provisional clade 2.3.4.6 designation.