The pandemic coronavirus’ debut wrought common havoc—not even seasonal flu viruses have been spared. Amid journey restrictions, quarantines, closures, bodily distancing, masking, enhanced hand washing, and disinfection, the 2020-2021 flu season was all however canceled. That meant not simply an unprecedented international lower within the variety of individuals sick with the flu but in addition a dramatic collapse within the genetic variety of circulating flu strains. Many subtypes of the virus all however vanished. However most notably, one complete lineage—one among solely 4 flu teams focused by seasonal influenza vaccines—went utterly darkish, seemingly extinct.
Researchers famous the absence final 12 months because the flu was nonetheless struggling to get better from its pandemic knockout. However now, the flu has come roaring again and threatens to trigger a very nasty season within the Northern Hemisphere. Nonetheless, the influenza B/Yamagata lineage stays lacking, in line with a examine printed this week within the journal Eurosurveillance. It has not been definitively detected since April 2020. And the query of whether or not it is actually gone extinct lingers.
What B/Yamagata’s absence would possibly imply for future flu seasons and flu photographs additionally stays an open query. For a fast refresher: 4 foremost kinds of seasonal flu have been circulating globally amongst people in recent times. Two are influenza kind A viruses: subtypes of H1N1 viruses and H3N2 viruses. The opposite two are influenza kind B viruses: offshoots of the Victoria and Yamagata lineages. (For a extra detailed clarification of influenza, try our explainer right here.) Present quadrivalent vaccines goal season-specific variations of every of those 4 kinds of flu viruses.
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