Covid’s Back. Who’s Most Likely to Get It Again?

A new study is offering data to back one of the core assumptions about the spread of Covid: The intensity of exposure to the virus matters, and vaccines and prior infections can only help so much — but they do indeed help.

The research, led by scientists at the Yale School of Public Health and published in Nature Communications, also reinforces the common-sense notion that masks and air filtration can augment the protection provided by a vaccine and lower the risk of getting the virus. Anyone watching Covid cases bubble back up in their community should take that to heart: Infections aren’t unavoidable, and the tools we’ve been using to protect ourselves are not just intuitive — and certainly shouldn’t be controversial. They’re increasingly backed up by evidence.