This article has been made free for everyone, thanks to Medium Members. For more information on the novel coronavirus and Covid-19, visit

How — and When — We’ll Know If a Covid-19 Vaccine Is Working

Phase 3 trials explained

Image for post
Image for post

“Vaccine effectiveness is typically lower in the real world.”

Written by

Staff writer at OneZero covering biotechnology. Previously, associate editor for biomedicine at MIT Technology Review.

Sign up for Your Coronavirus Update

By Medium Coronavirus Blog

The latest news, expert advice, and analysis to keep you safe, plus personal stories of life in a pandemic Take a look

By signing up, you will create a Medium account if you don’t already have one. Review our Privacy Policy for more information about our privacy practices.

Check your inbox
Medium sent you an email at to complete your subscription.

A real-time resource for Covid-19 news, advice, and commentary.

Get the Medium app

A button that says 'Download on the App Store', and if clicked it will lead you to the iOS App store
A button that says 'Get it on, Google Play', and if clicked it will lead you to the Google Play store