LONDON – Positive interim data from the U.S. trial of Astrazeneca plc’s COVID-19 vaccine have added yet more evidence it is effective in older adults and quelled concerns about serious thrombotic events that led countries in Europe to pause use of the vaccine earlier this month. Overall, the vaccine showed 79% efficacy in preventing symptomatic COVID-19, and was 100% effective in preventing serious disease and hospitalization. The effect was comparable across different ethnicities and age groups, with 80% efficacy in participants over 65 years of age. The analysis is based on 141 cases of COVID-19 infection.