The Centers for Disease Control and Prevention (CDC) has issued a notice of proposed rulemaking that would add certain highly pathogenic avian influenza strains (HPAIs) to the Department of Health and Human Services’ (HHS) list of select agents and toxins. In addition to listing any influenza virus that contains hemagglutinin (HA) from the Goose Guangdong/1/96 lineage, including wild-type viruses, CDC seeks to categorize as a Tier 1 select agent any virus containing HA from the HPAI H5N1 lineage “that were made transmissible among mammals by respiratory droplets in a laboratory.”

As directed by the Public Health Security and Bioterrorism Preparedness and Response Act of 2002, HHS maintains “a list of biological agents and toxins that have the potential to pose a severe threat to public health and safety.” Tier 1 designates those agents and toxins that “present the greatest risk of deliberate misuse with significant potential for mass casualties or devastating effect to the economy, critical infrastructure, or public confidence, and pose a severe threat to public health and safety.”

“We have determined that these influenza viruses have the potential to pose a severe threat to public health and safety,” states CDC in the notice. In particular, the agency highlights the increased pathogenicity of the HA molecule found in these strains that allows the virus to replicate outside the respiratory tract in humans. As the notice explains, “Extrapulmonary dissemination of HPAI H5N1 virus has been documented among some fatal human HPAI H5N1 virus infections.”’

Recognizing the effect of listing man-made transmissible HPAI H5N1 on vaccine development, CDC has specifically requested comments “on criteria that could be used for the exclusion of vaccine reassortants such as those well-characterized vaccine strains or backbones (e.g., PR8) that have been demonstrated to not pose a severe threat to public health and safety.” The agency will accept comments on the proposed rule until September 14, 2015. See Federal Register, July 16, 2015.