Pfizer and Moderna's vaccines are "highly effective" at reducing the risk of infection from COVID-19, according to the first large study of how Americans who have received a vaccine have fared in the U.S. outside of a clinical trial.
In a Centers for Disease Control study of just under 4,000 heath care workers, police, firefighters and other essential workers who received one of the two mRNA vaccines between Dec. 14 and March 13, the risk of infection went down by 90% two weeks or more after they received their second dose. Even the first dose alone provided significant protection, reducing the risk of infection by 80% two weeks after inoculation.
The study results are confirmation that the vaccines are effective against COVID-19 and provide optimism that as more Americans get vaccinated, the pandemic will end.