News AstraZeneca says US data shows COVID-19 vaccine prevents 79% of symptomatic disease March 22, 2021 Karen Weintraub, USA TODAY Comments Off on AstraZeneca says US data shows COVID-19 vaccine prevents 79% of symptomatic disease AstraZeneca's vaccine had a 79% efficacy rate at preventing symptomatic COVID-19 and was 100% effective in stopping severe disease and hospitalization