In that virus, one old surface protein, the H, was switched out for a new one in a process called reassortment.The strain went from H2N2 to H3N2.

• 病毒中古老的表面蛋白H蛋白在重配过程中基因交换发生变异，这样病毒株就从H2N2型转变成H3N2型。