#18,906
Although H9N2 cases are thought to be massively underreported in China - and around the world - the HK CHP's weekly avian flu report informs us of 2 more cases from the Chinese Mainland; the 20th and 21st case in the last 6 months (April 2025).
China tends to be cryptic in their public descriptions of avian flu cases, usually only providing an onset date, the patients age and gender, and the province where it occurred.Additional details on the patient's outcome, or exposures, are often only later revealed in the WHO's WHO: Influenza at the Human-Animal Interface Summary and Assessment. Typically, H9N2 presents as a mild infection, and is most often reported in children, although we've seen an increase in older adult infections in recent months.
For reasons that aren't clear, female cases have outnumber males by a considerable margin (cite).Despite decades of mandated use of vaccines, H9N2 remains poorly controlled in Chinese poultry (see J. Virus Erad.: Ineffective Control Of LPAI H9N2 By Inactivated Poultry Vaccines - China), which has led to the creation and spread of numerous genotypes.
While H9N2 remains far from our biggest pandemic threat, the CDC has designated 2 different lineages (A(H9N2) G1 and A(H9N2) Y280) as having some pandemic potential (see CDC IRAT SCORE), and several candidate vaccines have been developed.
Which is why we monitor these reports with considerable interest.
