Decoding Vaccine Efficacy Numbers

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What does it really mean when reports say that the Johnson & Johnson COVID-19 vaccine has an efficacy of 72 percent? It's actually not as straightforward as it might sound, and can be a little tricky to calculate, but the bottom line is that all three vaccines authorized in the U.S. greatly reduce the risk of getting COVID-19. Head over to The New York Times for a deeper dive into how efficacy percentages are calculated and what they mean.