LONDON — The University of Oxford and AstraZeneca's coronavirus vaccine was 90 percent effective in preventing COVID-19 In studies of more than 22,000 people in the UK and Brazil, AstraZeneca said in a November 23 press release.

Like Russia's Sputnik V vaccine and unlike Pfizer and Moderna's mRNA vaccines, the AstraZeneca-Oxford vaccine uses a modified adenovirus as a vector.

This animation explains how the AstraZeneca-Oxford vaccine works.