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AstraZeneca says U.S. trial data shows vaccine 79% effective

Last Updated Mar 22, 2021 at 7:07 am PDT

A nurse holds a dose of AstraZeneca vaccine before administering it to a tourist resort employee north of Port Louis, Mauritius, Wednesday Feb. 10, 2021. (Sumeet Mudhoo/L'express Maurice via AP)

Study out of U.S. suggests AstraZeneca vaccine is safer and more effective than originally thought

Trials for AstraZeneca's COVID-10 vaccine out of Britain last year showed 62 per cent efficacy

LONDON — There’s more encouraging data coming out about AstraZeneca’s COVID-19 vaccine, suggesting the drug may be safer and more effective than originally thought.

AstraZeneca says advanced trial data from a U.S. study on its vaccine shows it is 79 per cent effective in preventing COVID-19 symptoms, and 100 per cent effective in preventing severe illness.

This is higher than the trials out of Britain last year showing 62 per cent efficacy.

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The drugmaker says an independent committee also found no increased risk of blood clots among the more than 20,000 participants receiving at least one dose of the vaccine.

The U.S. study comprised 30,000 volunteers, 10,000 of which got dummy shots.

The early findings from the U.S. study are just one set of information AstraZeneca must submit to the U.S. Food and Drug Administration. An FDA advisory committee will publicly debate the evidence behind the shots before the agency decides whether to allow emergency use of the vaccine.

Related video: Trudeau says AstraZeneca COVID-19 vaccine is ‘safe and effective’

While the AstraZeneca vaccine has been authorized in more than 50 countries worldwide, scientists have been awaiting results of the U.S. study in hopes it will clear up some of the confusion about just how well the shots really work.

Health Canada approved the AstraZeneca vaccine on Feb. 26 for emergency use in this country.