WHO reported three new human infections with H9N2 avian influenza in China between 10 and 16 July, all in people WHO had been exposed to live poultry 1. Two of the patients were four-year-old boys and both recovered. The third, a 44-year-old man, remains in intensive care.
H9N2 is a different subtype from H5N1, the avian influenza this briefing has tracked through Cambodia's backyard-poultry cases , and the two do not belong in the same running total. H9N2 is a low-pathogenicity avian influenza that infects humans rarely and kills them more rarely still: 173 human cases worldwide since 2015, two deaths, 170 of those cases in China 2. Almost all of them have been young children with mild, self-limiting illness. Against that record, an adult in intensive care is an outlier, and a single severe case does not shift a subtype's risk assessment.
What sustains virological interest in H9N2 has little to do with its own lethality. Its internal gene segments are found inside H7N9 and inside several H5 reassortants, which means the virus functions as a parts supplier to influenza subtypes that hurt people far more. Every human infection is another opportunity for those segments to end up in a virus that transmits between people better than this one manages. The children WHO recover are, in that specific sense, as consequential as the man WHO has not.
