Science Health & Safety As booster shot protections wane, here's the latest research on a 4th vaccine dose 4:04pm February 21, 2022 by Michaeleen Doucleff Research News Science Health Share URL copied to clipboard! Copyright 2022 NPR. To see more, visit https://www.npr.org. 300x250 Ad More All Things Considered National You can sword-fight at this club. But no politics allowed Arts National In 'Wicked: Part I', Cynthia Erivo defies gravity — and convention — as Elphaba 300x250 Ad Support quality journalism, like the story above, with your gift right now. Donate