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Articles on vaccine effectiveness

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People getting vaccinated may still have questions about COVID-19 vaccines, like why it takes two doses — and then two weeks — to take full effect. THE CANADIAN PRESS/Ryan Remiorz

I work at a COVID-19 vaccine clinic. Here’s what people ask me when they’re getting their shot — and what I tell them

A medical student answers questions he gets asked at a COVID-19 vaccine clinic: Efficacy versus real-world effectiveness, immune response and how the mRNA vaccines compare to vaccines already in wide use.
Vaccine efficacy statistics are often based on the results of randomized controlled trials. (

How effective are COVID-19 vaccines? Here’s what the stats mean … and what they don’t

Vaccine efficacy is usually expressed as a percentage, but what is it actually measuring? Statisticians explain what the numbers mean, and what they say about how well a vaccine can protect us.

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