Since H1N1 swine flu viruses are antigenically very different from human H1N1 viruses, vaccines for human seasonal flu would not provide protection from H1N1 swine flu viruses.

• 由于H1N1猪型流感病毒跟人类H1N1病毒的抗原非常不同，所以季节性流感的疫苗未能对H1N1猪型流感病毒提供保护。