U.S. to Study Mix-and-Match Scenarios for Vaccine Booster Shots

Fully vaccinated Americans may know in the coming months whether they can mix and match follow-up shots, if variants in the virus that causes Covid-19 make those boosters necessary.

The National Institute of Allergy and Infectious Diseases is planning a study to determine what happens if someone receives one type of authorized Covid-19 vaccine, say Moderna Inc.'s jab, and is boosted with another like the Pfizer Inc. or Johnson & Johnson shot.

Emily Erbelding, director of the NIAID’s division of microbiology and infectious diseases, said the institute aims to have data in hand before the fall, which means studies would ...