In this week's episode, we explore the difference between vaccines that are effective for live and those that must be renewed yearly. The difference is viruses that mutate frequently, like the flu, and those that don't, like measles. We explore the mechanism that makes some viruses better at evading our immune system and the  tradeoff between high infection rate and high infection efficacy.

References:

• Frank SA, Bush RM. Barriers to antigenic escape by pathogens: trade-off between reproductive rate and antigenic mutability. BMC evolutionary biology. 2007 Nov 15;7(1):229. https://doi.org/10.1186/1471-2148-7-229
• Centers for Disease Control and Prevention. About estimated flu burden. CDC. February 25, 2026. Accessed July 14, 2026. https://www.cdc.gov/flu-burden/php/about/index.html
• Rodpothong P, Auewarakul P. Viral evolution and transmission effectiveness. World journal of virology. 2012 Oct 12;1(5):131.

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