By Jean-Paul McDonald
The United Kingdom is facing its first human case of an unusual swine flu strain, influenza A(H1N2)v, with the UK Health Security Agency (UKHSA) swiftly acting as part of their regular national flu report.
Despite instances of this strain, influenza A(H1N2)v, being reported worldwide since 2005, the case detected in the UK stands apart genetically from previous occurrences. UKHSA reports that this infection belongs to a unique clade (1b.1.1), differing from recent cases of influenza A(H1N2) found elsewhere but showing similarities to viruses seen in UK swine populations.
The individual affected by this distinctive strain experienced mild symptoms and has since made a full recovery. Nevertheless, the source of the infection remains a mystery, prompting authorities to launch immediate measures. Contact tracing efforts are underway to curtail potential virus spread, with heightened surveillance in medical facilities across North Yorkshire, a region situated in northern England.
Influenza A viruses, including subtypes such as H1N1, H1N2, and H3N2, are commonly present in swine. Occasionally, these viruses infect humans, typically through direct or indirect exposure to pigs or contaminated environments, according to UKHSA officials.
The broader subtype, influenza A(H1N2)v, has been reported in 50 human cases worldwide, including Canada. In late 2021, Manitoba reported an isolated human case of variant H1N2 to the Public Health Agency of Canada, with no evidence of human-to-human transmission.
While the world witnessed the 2009 "swine flu" pandemic, triggered by a different strain, H1N1, the current case remains unrelated to that outbreak. H1N1 now circulates seasonally among humans and is distinct from the virus strains observed in swine populations.