AstraZeneca says advanced trial shows its COVID-19 vaccine is 79% effective

London — British drug manufacturer AstraZeneca says advanced trial data from a U.S. study on the COVID-19 vaccine it developed along with Oxford University shows it is 79% effective. Although the vaccine has been authorized in more than 50 countries, it hasn' yet been given the green light in the U.S.

The U.S. study comprised 30,000 volunteers, 20,000 of whom were given the vaccine while the rest got placebo shots. The results were announced Monday. In a statement, AstraZeneca said its vaccine had a 79% efficacy rate at preventing symptomatic COVID and was 100% effective in stopping severe disease and hospitalization.