Pfizer, Moderna Vaccines Stop Infections in Real-World Study

Covid-19 vaccines from Pfizer Inc. and Moderna Inc. effectively prevented coronavirus infections, not just illness, with substantial protection evident two weeks after the first dose, government researchers said.

Two doses of the vaccines provide as much as 90% protection against infection, according to data from U.S. Centers for Disease Control and Prevention study published Monday. Earlier clinical trials had established that the shots also prevent illness, hospitalizations, and deaths.