The Slatest

New AstraZeneca-Oxford Vaccine Up to 90 Percent Effective in Preventing COVID-19

Vials labeled "COVID-19 VACCINE" next to syringes, with the University of Oxford and AstraZeneca logos in the background
More good news on the vaccine front. Justin Tallis/Getty Images

More good news on the coronavirus vaccine front, as British drugmaker AstraZeneca announced Monday that late-stage clinical trials showed its vaccine was, on average, 70 percent effective in preventing COVID-19. The effectiveness of the vaccine developed with Oxford University depended on the dose. Some of the 20,000 trial participants were given a single dose, and in those cases the vaccine was 62 percent effective. Under a second dosing regimen, two doses were administered, first a half-dose and then a second standard dose a month later, which proved to be 90 percent effective, according to the company. Oxford and AstraZeneca also said the study had shown the vaccine to reduce asymptomatic infections, a significant driver of the spread of the virus.


The AstraZeneca-Oxford vaccine is the third vaccine candidate to report successful clinical trials this month, following Pfizer and Moderna’s announcements, though this latest vaccine will likely be cheaper and far easier to distribute. “While the results released by AstraZeneca indicate somewhat lower efficacy … the vaccine can be stored and transported at normal refrigerated conditions for up to six months,” the Washington Post notes. “That could make it significantly easier to roll out than Pfizer’s vaccine, which has to be stored at minus-70 degrees Celsius, or Moderna’s, which is stable in refrigerated conditions for only 30 days and must be frozen at minus-20 degrees Celsius after that.”

“AstraZeneca has said it aims to bring data from its studies of its vaccine being conducted overseas to the Food and Drug Administration—which would mean that the agency will likely review and authorize a vaccine before late-stage data are ready on how well the vaccine works in American participants,” according to the New York Times. “British regulators already have been conducting a so-called rolling review of the vaccine.” The U.K. government has already preordered 100 million doses of the vaccine; AstraZeneca says it will expand production to make 3 billion doses for global distribution in 2021.