A single dose of Pfizer’s or Moderna’s Covid-19 vaccine was 80% effective in preventing coronavirus infections, according to a new Centers for Disease Control and Prevention study of vaccinated health-care workers.
The effectiveness of partial immunization was seen two weeks after the first dose, according to the CDC, which looked at nearly 4,000 health-care personnel, first responders and front-line workers between Dec. 14 and March 13. The health-care personnel and other essential workers in the study, which was published Monday, had no previous laboratory documentation of Covid-19 infection.
