CDC Acknowledges H3N2v Human to Human Transmission
August 24, 2012
The three instances of likely person-to-person spread of H3N2v were recently identified during investigations of cases and their household contacts and are not epidemiologically linked to one another. In all three cases, transmission is thought to have occurred from one person to another person without further spread to additional people. Each of these three instances of likely person-to-person spread happened between 2 people living in the same household, with the initial infection in each household being associated with pig exposure at an agricultural fair.
The above comments are from the CDC August 24 update, which acknowledges limited human to human (H2H) transmission of H3N2v as noted above. However, this approach of following the CDC biased sample who had extensive swine contact severely limits investigation. Most families with H2H transmission will be excluded, because family members had some sort ofg swine exposure. The CDC approach is similar to other countries limiting confirmed cases of H5N1 by limiting testing. Moreover, the 2012 cases are due to the sub-clade initially identified in a West Virginia cay care center where there was no swine exposure, yet ILI was identifed in 23 contacts of the index case, so extenisive H2H has already been demonstrated for this sub-clade.