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EU finds possible link between the AstraZeneca COVID-19 vaccine and rare blood clots

The European Medicines Agency said a very rare side effect of the AstraZeneca COVID-19 vaccine is "unusual blood clots with low blood platelets." That's a blow to low- and middle-income countries because the vaccine is inexpensive, easier to transport and store and is also 79 percent effective at preventing infections. Boston University's Dr. Nahid Bhadelia joins Nick Schifrin to discuss.

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  • Judy Woodruff:

    The global push to get people vaccinated for COVID hit a new set of concerns today.

    Nick Schifrin reports on why the AstraZeneca shots are critical around the world.

  • Nick Schifrin:

    Today, the European Medicines Agency said a very rare side effect of the AstraZeneca vaccine is — quote — "unusual blood clots" with low blood platelets.

    That could be a blow to global vaccine efforts, especially low- and middle-income countries, because AstraZeneca is relatively inexpensive and easy to store and transport. It's 79 percent effective at preventing symptomatic infections, and 25 million people in Europe have already received it.

    For more on today's news, we turn to Dr. Nahid Bhadelia, medical director of the Special Pathogens Unit at Boston Medical Center and an associate professor of infectious diseases at Boston University School of Medicine.

    Thank you very much. Welcome back to the "NewsHour."

    The European Medicines Agency concluded that unusual blood clots with low blood platelets should be listed as a very rare side effect of AstraZeneca.

    How significant is that announcement?

  • Dr. Nahid Bhadelia:

    Thanks so much, Nick.

    So, what they're saying is that there's a plausible link, not confirmed, but plausible link between the AstraZeneca vaccine and what they're seeing, which is blood clots that don't manifest similar to what we're seeing patients who are high-risk because of their weight or their travel or immobility, but these are blood class seen in younger patients.

    And then the mechanism, proposed mechanism, is that, after you get the vaccine, you may develop antibodies that attack a part of your blood that allows your blood to clot, the platelets, and hence it leads to risk of clots in some areas, but risk of bleeding in others.

    And so the reason why this plausible link exists is because they're seeing those with higher rates above what may be seen in the general population. However, the numbers are still very small.

    Just to put this into perspective, the numbers that the European medical agency has used, in — one in 100,000 people that receive the AstraZeneca vaccine may see this, and one — and according to the U.K. regulators, they released the numbers of one in 250,000 people who may receive this vaccine may potentially see this.

    Compare that to the risk, for example, from blood clots from flying, which, by some studies, is one in 5,000, so still a very rare side effect, but definitely something to look out for, if that link exists, and more studies are required to potentially connect the two better.

  • Nick Schifrin:

    So, understanding the risk is rare, is there a way to mitigate it?

  • Nahid Bhadelia:

    One of the ways that the British regulators have approach this is, they have decreased eligibility to those over 30, with the understanding that these types of cases are being seen mostly in those over — over — under 60, and potentially in younger patients.

    And because in younger patients, one of the — one of the ways that these clots manifest is something called cerebral venous sinus thrombosis, a condition that sometimes is seen in young women who are on birth control.

    And so I think what they're trying to do is mitigate the risk by potentially making only those over 30 eligible for this. I don't — is that the right way to go about it? I still think the risk — the benefits outweigh the risks, because, as both the WHO, as well as the European medical agency have said, the risk of mortality from COVID still outweighs any risk of mortality from these rare blood clots that we're seeing.

  • Nick Schifrin:

    And we saw the E.U. as well and the U.K. ultimately say that, yes, the benefits outweigh the risks.

    Do we know, though, how this compares to other vaccines?

  • Nahid Bhadelia:

    That's right.

    So, there are some numbers that were shared in the same report. And so you have seen rare — again, I think the denominator is different, right? And I think you're seeing small numbers, two or three cases reported in Johnson & Johnson in the 4.5 million that might have been released of vaccines.

    I think you're seeing a handful of these, again, in the mRNA vaccines of the millions that are released. You're not seeing it at the same rates, that I think you're seeing almost a threefold increase in AstraZeneca's group from the denominators we have currently — just keep that in mind — and also in terms of the way that we have been looking for them.

    But I do think it raises the importance of if, if there is a link, and particularly with AstraZeneca, what we should do as next steps is put that guidance out to practitioners and to patients who are getting it that, about four to 20 days after you get this vaccine, if you see these types of side effects, headaches, visual changes, right, swelling in your feet — one of the other side effects is, if there's a blood clot in the abdomen, there might be abdominal pain — to keep an eye out for that, because that's going to help mitigate risk and identify people who may be at risk earlier as well.

  • Nick Schifrin:

    As we described, AstraZeneca is going to be distributed all over the world, especially low- and middle-income countries. What's the impact of today's news on fighting COVID globally?

  • Nahid Bhadelia:

    Well, I'm hoping not a lot, right, again, because I think the benefits do outweigh the risks.

    But it does raise an important question of, like, if there are these rare side effects — again, pretty rare, but they do exist — if they do end up existing, how do we, in a setting where a health care system may already be strapped, ensure that there's surveillance for these rare incidences and find people who potentially have these side effects and bring them to care early?

    And it'd be interesting to see if other countries take the same stance that the U.K. did, which is that they decrease the eligibility to those above 30. It also will be interesting to see how the U.S. FDA is going to respond to that, both the EMA data, as well as the take by the U.K. regulators.

  • Nick Schifrin:

    You just mentioned the U.S. FDA.

    AstraZeneca, of course, has not been approved by the FDA. Where do things stand with that approval?

  • Nahid Bhadelia:

    So, as far as we know and what we last heard from AstraZeneca, there are — they are on target in submitting their submission for approvals to the FDA.

    It's going to be interesting to see, because in the U.S. trials of AstraZeneca, right — it was about 30,000 people — these were not seen, again, because there are such — these are such rare side effects,if they exist, that, in that group, in that trial, blood clots, at least from the top-line results that were shared so far, there did not seem to be a difference in blood class between people who got the vaccines compared to people who did not get the vaccines.

    Now, that means that, is the U.S. FDA going to reach out for this data from the European medical agency in making part of their decisions? I think that's an unclear — if I were to bet — and, again, not related to — just as an opinion, rather than a known fact — I think it's likely that they will end up approving the vaccine.

    The question is, will we have widespread distribution of those vaccines, given that we already have so many candidates that are under production and in distribution here in the U.S.?

  • Nick Schifrin:

    Dr. Nahid Bhadelia, thank you very much.

  • Nahid Bhadelia:

    Thank you.

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