alleryStart learning →Why must the influenza vaccine be reformulated for each flu season?
ASurface molecules of the virus mutate
BThe vaccine expires after one year
CMemory T cells die within a year
DAntibodies to flu are never made
Answer & Solution
Correct answer: A. Surface molecules of the virus mutate
1. Pathogens have evolved ways to evade immune responses, and mutation is one of the main methods.
2. The surface molecules of viruses mutate continuously.
3. Influenza therefore changes enough each year that the flu vaccine for one year may not protect against the flu common to the next.
4. New vaccine formulations must be derived for each flu season, which is why the shot is repeated annually.
_Source: OpenStax Anatomy and Physiology (CC BY 4.0), Ch 21 "The Lymphatic and Immune System", section 21.5 The Immune Response against Pathogens_
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