Oxford, AstraZeneca Vaccine Gets U.K. Nod. How Is It Different Than Other Shots?

The U.K. authorized a Covid-19 vaccine developed by AstraZeneca AZN 1.05% PLC and the University of Oxford, the second shot to get the green light in the country and the third to be cleared for emergency use in the West. The authorization follows a similar one in the U.K. earlier this month for a vaccine made by Pfizer Inc. and BioNTech SE. The Pfizer shot and one by Moderna Inc. have both been authorized in the U.S.

The U.K. authorization of AstraZeneca’s shot comes as Britain finds itself at the center of concerns over this winter’s fast-spreading coronavirus cases, both in Europe and the U.S. The U.K. earlier this month said it had identified a new variant of the virus that appeared more contagious than previously known variants. U.K. officials have said a fast vaccine rollout could help curb the spread of this new virus form.

What does the authorization mean?

AstraZeneca and Oxford can now distribute their two-shot vaccine across the U.K. The two British organizations have long made plans for manufacturing and distribution in the U.K., and that should add significantly to existing vaccine supplies from Pfizer and BioNTech.

Is this vaccine effective against the new variant identified in the U.K.?

British officials say the new mutations appear to make the virus more contagious. But they say the variant should be just as vulnerable to the several vaccines that have been deployed against the coronavirus, including AstraZeneca’s.

When will it be available in the U.S.?

Not immediately. The Food and Drug Administration is waiting to see data from human trials now being conducted in the U.S. before reviewing the vaccine for use. AstraZeneca has still been recruiting trial participants but, given rising infections, could have the necessary data for the FDA by February.

How many doses can AstraZeneca roll out?

The company previously said it had around four million doses ready for distribution in the U.K. and plans to ramp up deliveries from that. A person familiar with the plans said company executives expect that by late January, the company can provide around four million doses a week. The U.K. has preordered up to 100 million doses.

What’s the difference between the AstraZeneca-Oxford shot and the Pfizer vaccine?

Both require two doses. AstraZeneca’s vaccine is more similar to traditional vaccine technology: introducing a weakened strain of a virus, in this case from a chimpanzee, into the body to trigger an immune response. Vaccines made by Pfizer-BioNTech and Moderna, both of which are deployed in the U.S., use a newer technology called messenger RNA to trigger an immune response.

Is AstraZeneca’s shot proven to be safe and effective?

Human trials show the shot is safe and that it was about 62% effective for the majority of trial participants who were given it. That compares with 95% for Pfizer and 94% for Moderna. A small subset of Oxford trial volunteers aged 55 and younger were given a half dose followed by a full dose. The half-dose regimen showed the vaccine to be 90% effective, though scientists said they couldn’t fully explain the better result and want to study it more.

Earlier

The U.K. became the first Western nation to vaccinate patients against Covid-19. WSJ explains how the country is planning to roll out the BioNTech-Pfizer vaccine at record speed, making it a test case for the rest of the world. Photo: Jacob King/Bloomberg News (Originally published Dec. 8, 2020)

Write to Jenny Strasburg at jenny.strasburg@wsj.com

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