The Claim:
Aunt Betsy had chickenpox as a child, and her doctor told her she doesn’t need the vaccine because she can assume she already has immunity. Since she had a case of the flu last year, she figures she doesn’t need a flu vaccine.
The Facts:
Aunt Betsy doesn’t need a chickenpox vaccine–it’s true. The chickenpox virus (varicella) is pretty stable–not changing significantly enough or fast enough for her body’s immune system to be unable to recognize it, even after all these years.
Influenza, though, is different. The virus mutates frequently, and those mutations affect how well our immune system will recognize the virus from year to year. It is very likely that in subsequent years, if you are exposed to an influenza virus, it would have changed substantially enough that your immune system won’t protect you well enough. Get your flu shot, Aunt Betsy. And maybe a Shingles vaccine, too.