Yearly Vaccination of Humans for Influenza Viruses is Necessary Because

Question

Yearly vaccination of humans for influenza viruses is necessary because
A) of an increase in immunodeficiency diseases.
B) flu can generate anaphylactic shock.
C) surviving the flu one year exhausts the immune system to nonresponsiveness the second year.
D) rapid mutation in flu viruses alters the surface proteins in infected host cells.
E) flu leads to autoimmune disorders.

Accepted Answer

Rapid mutation in flu viruses alters the surface proteins in infected host cells, making it difficult for the immune system to recognize and fight off the virus from year to year, hence requiring yearly vaccinations to keep up with the changing strains.