H1N1 Definition
āchwunenwun
noun
Any of various strains of influenza virus including those that most commonly cause influenza in humans; specif., a pandemic strain originating in North America in 2009 and containing genes from swine, bird, and human influenza viruses.
Webster's New World
Origin of H1N1
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The strain classified as containing hemagglutinin type 1, and neuraminidase type 1.
From Wiktionary