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AstraZeneca vaccine 79 percent effective at preventing COVID symptoms, U.S. trial shows

In the largest COVID vaccine trial yet, AstraZeneca's vaccine was 79 percent effective in preventing symptomatic infections, the company announced Monday. AstraZeneca's vaccine has also been shown to be extremely effective at preventing the most serious outcomes from COVID-19, the company said. William Brangham discusses the latest inoculation news with Boston University's Dr. Nahid Bhadelia.

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  • Judy Woodruff:

    AstraZeneca announced today that their vaccine is not only safe, but extremely effective at preventing the most serious outcomes from COVID-19.

    In the largest COVID vaccine trial yet, AstraZeneca's was 79 percent effective in preventing symptomatic infections. The company will soon seek approval in the u.s

    And, as William Brangham tells us, the question now is where it fits into the overall distribution plan in the U.S. and internationally.

  • William Brangham:

    That's right, Judy. We haven't seen the raw data yet, just what the company has put out.

    But AstraZeneca's latest trial included 32,000 people, and it prevented both hospitalizations and deaths. And this is important because this vaccine is a crucial part of the international effort to distribute shots to less wealthy countries.

    Dr. Nahid Bhadelia is the medical director of the Special Pathogens Unit at Boston Medical Center and an associate professor of infectious diseases at Boston University School of Medicine.

    Dr. Bhadelia, great to have you back on the "NewsHour."

    Do you share the judgment that this is another piece of very good news, that we now have a fourth vaccine that has proven quite effective against COVID-19?

  • Dr. Nahid Bhadelia:

    I do, William.

    If the FDA's evaluation holds up the data that we're seeing today, it's good news because it adds a fourth candidate to the U.S. fight at a time that we're rushing to cover our population with immunity, but it's been called the vaccine for the world, because, as you said, it is making up the lion's share of vaccines distributed by COVAX, the WHO's utility to try to get the vaccines out to the most of the rest of the world.

    They — it happens to be about $2 to $3 per dose. It can be refrigerated at regular refrigerators — freezers — sorry — refrigerators for about six months, ability to get out to most sort of isolated parts of the world.

    And for all those reasons and the fact that it serves as another data point showing efficacy and safety, this is a big plus for global health and it's a big plus for U.S. health as well.

  • William Brangham:

    Indeed, we could use all the big pluses we can get right now.

    I know there had been some concern recently over some blood clot side effects. This caused several European nations a week or so ago to stop using this vaccine. European regulators looked at it, didn't seem to think that there was any real concern about side effects.

    Did this current trial from AstraZeneca address any or show any additional side effects for this vaccine?

  • Nahid Bhadelia:

    Well, William, I think it's good to cover why there was this concern, right?

    I think what we saw from AstraZeneca and the U.K. authorities last Sunday was — about a week ago was that the numbers of people who developed blood clots was the same among the 17 million people who've gotten this in the U.K. compared to those in the general population.

    The concern from the E.U. authorities was that they were seeing these blood clots that are often found in younger patients that just are rare diseases that occur among the general population. And what the European Medicines Association has been able to show is that there really does not seem to be a causal link between the two.

    And what this trial does is, at least in this well-controlled setting, shows you that this is — there — it's unlikely that this is a common side effect, and the fact that it does not occur even in this controlled setting at higher frequency among people who receive the vaccines compared to the placebo.

  • William Brangham:

    We know, of course, there are these so-called variants of concern from several different regions around the world.

    What is their understanding of how this vaccine does against those variants?

  • Nahid Bhadelia:

    The most common variant that we're seeing here in the U.S. is the one that was originally discovered in the U.K., the B117.

    The good news on that front is that that particular variant seems to be maintained — it's that all the vaccines on the market, including the AstraZeneca, seem to maintain good activity against that.

    The ones we're concerned about is the one that was initially discovered in South Africa, the 1351 and the P.1 from Brazil, both of which, in the laboratory settings, already show lower efficacy for Moderna, Pfizer and for AstraZeneca, in prior studies in South Africa, as well as in Latin America, have shown a drop in efficacy.

    The important thing is that their efficacy against severe disease, hospitalizations and deaths still seems to hold out. So, as the companies, both AstraZeneca and others, work on their boosters to address those variants, I think it's still going to be important to get this version of the vaccines out, because it's going to help us protect the health systems and more severe disease.

  • William Brangham:


    As you're saying, if it protects against hospitalizations and deaths, in the end — I mean, of course, we want to prevent infections, but stopping people from going to the hospital or dying is obviously enormously important.

    As we were saying before, the FDA has not approved this shot. No one in the U.S. is currently getting the AstraZeneca vaccine. They are going to apply for an emergency use authorization. Do you think that approval will come? And do you think we will start seeing this vaccine deployed here?

  • Nahid Bhadelia:

    Yes, I think that, if the FDA finds that the data holds up, it is likely to get an emergency use authorization.

    Now, the more — other — the more important question is, how commonly will it be used? So, 30 million doses of the vaccine already sit here on U.S. ground. And we know that the Biden administration has said that, by May 1, even projections based on existing approved vaccines, there should be enough for all Americans.

    What the White House adviser Andy Slavitt today said today that is, they're not going to — because they're concerned that they want to make sure the manufacturing for the existing vaccines hold up, they're not going to make decisions yet about whether or not AstraZeneca is going to be needed or not.

    Likely, I think it may be deployed in those settings if manufacturing or other vaccines don't work out. One thing that I do hope happens is that those surplus doses that are sitting around, I hope we send it around to the rest of the globe, because transmission anywhere is going to be a threat to all of us getting back to normal.

  • William Brangham:

    All right, Dr. Nahid Bhadelia of the Boston University School of Medicine, thank you very much for being here.

  • Nahid Bhadelia:

    Thank you, William.

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