AstraZeneca vaccine poised to become global leader

BOSTON — It is already in emergency use in more than 70 countries around the world, and AstraZeneca’s Covid-19 vaccine is a step closer to regulatory approval in the United States.

Monday, the company announced results of its U.S. Phase III trial, which involved more than 32,000 participants.

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The company says its vaccine was 79% effective at stopping symptomatic infections and 100% effective at halting severe infections and hospitalizations. While all age groups did well on the vaccine, those 65 and older responded particularly well, with an 80% overall effectiveness rate.

“Most importantly, like the other vaccines, it prevented severe disease,” said Mark Siedner, MD, of Massachusetts General Hospital. “It prevented hospitalizations, it prevented deaths. That’s what we wanted to see. And no major side effects in this study.”

But there has been a recent controversy with side effects -- with some 30 cases of blood clots developing in people vaccinated with the AstraZeneca product in Europe.

“We have to be very careful not to attribute common events that happen to occur after receiving the vaccine to the vaccine itself,” said Daniel Kuritzkes, MD of Brigham and Women’s Hospital. “Thirty or so blood clots in the context of millions of people receiving a vaccine is not a safety signal. And that’s what the European Medicines Authority concluded.”

The EMA backed up the safety of the AstraZeneca vaccine last week, after investigating the blood clot issue.

“I think people can be really reassured that the AstraZeneca vaccine is safe and that blood clots are not a problem with this vaccine,” Kuritzkes said.

Where the AstraZeneca vaccine might have a problem is with some of the Covid variants.

“The B.1.1.7 (British variant) this seems to do fine,” said Beth Kirkpatrick, MD, one of the U.S. investigators of the AstraZeneca vaccine, and a professor in the Department of Microbiology and Molecular Genetics at the University of Vermont Larner College of Medicine. “This AstraZeneca vaccine is not that great for the variant that was originally found in South Africa. So that is one thing we are going to need to watch. And this company, AstraZeneca, like all the others, are already thinking about retrofitting their vaccines to kind of keep ahead of the variants.”

However, Kirkpatrick predicts the AstraZeneca vaccine will prove a “global workhorse” against Covid-19.

“It is relatively fast to make,” she said. “Relatively easy to store and relatively inexpensive.”

And AstraZeneca is poised to make lots of it -- important, given pandemic control will require a truly worldwide vaccination effort

“They have 20 industrial manufacturing nodes for this vaccine, all through the world,” Kirkpatrick said. “And so I think as we realize how important it is to start vaccinating everybody not just sort of those in a single country, this vaccine’s going to have a big role in that.”

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