Question: what is the difference between h1n1 and influenza a?
Answer: Flu (influenza) viruses are divided into four broad categories: influenza A, B, C or D. Influenza A is the most common type. H1N1 flu is a subtype of influenza A. Subtypes of influenza A are categorized based on two proteins on the surface of the virus, hemagglutinin (H) and neuraminidase (N).