What about Mrs. Hogan's ideas about flu shots?
D) Flu shots prevent flu.
Sorry...
Unfortunately this is not always true. Even when the vaccine viral strains match the epidemic strain (usually the case, thanks to worldwide selection based on 6 months prior southern hemisphere flu activity), they induce serum IgG antibody which protects the lungs, but not mucosal IgA antibody which protects the upper respiratory tract. In those cases where flu shots do not prevent infection, they usually do decrease severity and duration of the illness.