Nov. 23, 2020 -- Pharmaceutical company AstraZeneca announced Monday morning that its coronavirus vaccine is on average 70% effective in preventing COVID-19.

The news comes after Pfizer and Moderna reported their vaccines are about 95% effective.

AstraZeneca’s results came from an interim analysis of two late-stage clinical trials.

The vaccine, developed with the University of Oxford, was tested using two different dosing plans. One group of 2,700 clinical trial participants received a half dose, followed by a full dose a month later. For that group, the vaccine was 90% effective. The other group of nearly 9,000 participants received two full doses a month apart. For that group, the vaccine was 62% effective. A combined analysis showed that the vaccine was 70% effective on average.

Overall, researchers reported 131 COVID-19 cases in the interim analysis, and no hospitalizations or severe cases. No serious safety events have been confirmed after a temporary pause in trials in September to investigate a potential issue.

“These findings show that we have an effective vaccine that will save many lives,” Andrew Pollard, PhD, chief investigator of the trial, said in the statement.

The company is also ramping up vaccine production to manufacture 3 billion doses in 2021. The vaccine can be stored and transported at typical refrigeration temperatures (2-8 C, or 26-46 F) for 6 months and given to patients in health care settings.

AstraZeneca’s vaccine is cheaper, according to The Associated Press. Based on agreements with governments and health organizations, the cost is about $2.50 per dose. Pfizer’s vaccine costs $20 a dose, and Moderna’s is $15 to $25, the AP reported.

The vaccines also work in different ways. AstraZeneca’s uses a weakened version of the common cold, which is combined with the spike protein found on the surface of the virus that causes COVID-19. The vaccine prepares the immune system to recognize the spike protein and attack the virus later if infected.

The Pfizer and Moderna vaccines, on the other hand, use a new messenger RNA technology that teaches the body how to make that spike protein so the body can recognize it and fight it. The mRNA vaccines contain a fraction of the virus and aren't made with infectious particles, which makes them safer for patients.

Researchers will continue to collect and analyze data to help make the vaccine better, according to the announcement. AstraZeneca is now preparing paperwork to submit data to agencies around the world, including the World Health Organization's accelerated pathway to help make sure low-income countries can get the vaccine. The company will also submit a full analysis of interim results to a peer-reviewed journal for publication.

An independent Data Safety Monitoring Board confirmed that the analysis met the goal of preventing COVID-19 after two doses of the vaccine. The interim analysis was based on data from clinical trials in the UK and Brazil, and other trials are underway in the U.S., Japan, Russia, South Africa and Kenya. AstraZeneca expects to enroll up to 60,000 trial participants globally.

Show Sources

AstraZeneca: “AZD1222 vaccine met primary efficacy endpoint in preventing COVID-19.”

The Associated Press: “3rd major COVID-19 vaccine shown to be effective and cheaper.”

USA Today: “Pfizer and Moderna use mRNA in their COVID-19 vaccines. This never-before-used technology could transform how science fights diseases.”

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