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Commentary
Rapid
H3N2 Spread In Japan Raises Concerns
Recombinomics
Commentary 14:08
November 8, 2010
Six patients had died of any psychiatric ward.
The above translation provides an update on the H3N2 outbreak at a psychiatric hospital in Akita, Japan. A vaccination campaign was launched to slow the spread, and it remains unclear if this approach contributed to the spike in deaths of elderly patients at the facility. An increase in deaths in the elderly was expected this season, but six deaths in six days in the relatively small population raised concerns that the H3N2 had become more lethal.
The rapid spread was acknowledged in media reports and influenza-like illness levels have reached epidemic levels in adjacent Hokkaido as well as Osaka in the south. These rapid increases may be linked to a sub-clade emerging worldwide (see list here) which has three members which have been classified as ‘low reactors”, signaling evolution of the Perth/16/2009 strain, which is the current H3N2 vaccine target. This target was identified in early 2009, and the isolates from the spring/summer of 2010, including A/HOKKAIDO/17/2010, had evolved away from this strain. It is likely that the current H3N2 in circulation has evolved further, which would limit the effectiveness of the current vaccine as well as antibodies directed against earlier H3N2 strains, such as the Brisbane/10 strain that was widespread prior to replacement by Perth/16.
The deaths and rapid spread of H3N2 in the hospital in Akita have raised concerns that similar outbreaks will soon be reported worldwide. The H3N2 strains in circulation have evolved away from the vaccine target and prior H3N2 strains, and the low number of elderly deaths last season due to a decline in H3N2 infections and cross reacting antibodies to pH1N1, raises concerns of significant increases in H3N2 deaths in the elderly population.
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