The delta variant is now the most-prevalent strain of COVID-19, causing a handful of so-called “breakthrough” infections in fully-vaccinated people. Unvaccinated people account for 97% of severe cases of the virus. How worried should you be about infections as the delta variant continues to dominate? And is it time to mask up again? Guest: Susan Matthews, Slate’s news director.  If you enjoy this show, please consider signing up for Slate Plus. Slate Plus members get benefits like zero ads on any Slate podcast, bonus episodes of shows like Slow Burn and Dear Prudence—and you’ll be supporting the work we do here on What Next. Sign up now at slate.com/whatnextplus to help support our work. Learn more about your ad choices. Visit megaphone.fm/adchoices