Influenza a virus subtype h3n2

When WHO officials choose the strains of influenza to include in the yearly flu vaccine, they choose two strains of influenza A (one variant of H1N1 and one variant of H3N2) and one or two strains of influenza B. Most flu vaccines contain three strains of influenza, but the quadrivalent vaccine and the A Word From Verywell Influenza is a difficult virus. It changes so frequently that it is hard to identify and treat—and even harder to develop the vaccine months in advance of flu season. H3N2 is one subtype of the influenza virus that often causes significant illness. When it is the dominant strain causing illness during a given year, those flu seasons are often more severe. It's important to take steps to protect yourself and your family from the flu each year, no matter which strain is making people sick.