, Columnist
How Good Are Vaccines? Try 99.9999% Effective
That 95% efficacy number isn’t the whole story.
Small miracle.
Photographer: Leon Neal/Getty Images
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I have a friend who works in the New York City Department of Education’s Covid-19 “situation room” — tracing cases, informing contacts and so on. She’s really good at her job, which is why I was surprised to hear her make a strange statistical assertion: Since the Pfizer and Moderna vaccines are 95% effective, one in 20 vaccinated people are going to get Covid.
That’s wrong, dangerously so. And given that an expert who works in the area every day can make such a mistake, I figure it’s worth some explaining.