ScienceHerd immunity and why crosswords don't workTo play this audio please enable JavaScript, and consider upgrading to a web browser that supports HTML5 videoScienceConor Dillon | Gabriel Borrud05/31/2021May 31, 2021Know someone who does puzzles to "keep their brain sharp"? We've got bad news for them. Also, it's time to forget herd immunity and embrace the idea of booster shots.https://p.dw.com/p/3uETUAdvertisement