Pfizer’s Covid-19 Booster Shot Improves Immunity, Israeli Study Suggests

TEL AVIV—Early data from Israel suggests a booster shot of Pfizer Inc.’s Covid-19 vaccine can significantly improve immunity in those aged 60 and above, as the U.S. and other countries plan additional doses to increase protection against the highly infectious Delta variant.

Israel was one of the first countries late last month to authorize a third Pfizer dose for the elderly who were fully vaccinated with the recommended two shots, after indications that vaccine protection against severe illness has waned.