Pfizer, Moderna COVID-19 vaccines highly effective after first shot in real-world use - U.S. study

FILE PHOTO: Vials with Pfizer-BioNTech and Moderna coronavirus disease (COVID-19) vaccine labels are seen in this illustration picture taken March 19, 2021. REUTERS/Dado Ruvic/Illustration/File Photo

(Reuters) - COVID-19 vaccines developed by Pfizer Inc with BioNTech SE and Moderna Inc reduced risk of infection by 80% two weeks or more after the first of two shots, according to data from a real-world U.S. study released on Monday.

The risk of infection fell 90% by two weeks after the second shot, the study of nearly 4,000 U.S. healthcare personnel and first responders found.