National Science Health & Safety Scientists May Have Found A Marker Of How Effective COVID-19 Vaccines Are 4:40pm August 10, 2021 by Joe Palca Science Health Medical Treatments National Share URL copied to clipboard! Copyright 2021 NPR. To see more, visit https://www.npr.org. 300x250 Ad More All Things Considered Economy More Americans are falling behind on credit card bills by Scott Horsley Books Novelist Claire Messud excavated her family history. A fictional book is our reward 300x250 Ad Support quality journalism, like the story above, with your gift right now. Donate