The reason that acquired immunity to influenza does not effectively prevent future infections...?

The reason that acquired immunity to influenza does not effectively

prevent future infections with the virus is that:

A) antigenic shift occurs frequently and produces new strains

B) mutations occur that modify antigenic determinants of the human

strain influenza

C) influenza vaccines are rarely effective.

D) different species of influenza appears every year

I wanna say B) or D), but both sound good... But... with D), is it new SPECIES or are they mutations, like in B)? -_-;

1 Answer

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  • 8 years ago
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    I'm pretty sure its mutations, mutations create the new species.

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