Explain why each choice (a-d) is correct or incorrect. A flu vaccine is needed seasonally to be effective but a polio vaccine is only needed once.  The best explanation of this is a. Flu vaccine is substantially weaker than the polio vaccine. b. The polio virus is substantially weaker than the flu virus. c. Exposure to flu vaccine produces no memory cells from proliferating B lymphocytes. d. The flu has several strains that change seasonally.

The BCG vaccine is used for protection against A. diphtheria. B. poliomyelitis. C. tuberculosis. D. mumps. E. hepatitis. O O O

Tuberculosis and the effect tuberculosis vaccination hesitancy has had on vaccine-preventable diseases in the US?

From: "Why our flu vaccines can't keep up" What is the most likely explanation for why the smallpox and polio vaccines have high long-term effectiveness, while the influenza vaccine has lower effectiveness and is only effective for a shorter time period? Smallpox and polio are caused by a virus, but flu is caused by a bacterium. The smallpox and polio vaccines are manufactured using more modern techniques than the flu vaccine. O The influenza virus mutates more rapidly than the smallpox and polio viruses. O The symptoms of flu are more severe than those of smallpox and polio.