A highlight from Episode 166: J&J's vaccine pause, talking about remote risks, & why no new drugs for Covid-19
With another unexpected volatile development involving kobe. Vaccines this time. Trouble has come for johnson and johnson on tuesday. The fda and the cdc to temporarily halt vaccinations with the j. covid nineteen vaccine because of concerns about a rare but serious clotting problems seen in some people who had received the vaccine on wednesday. A committee of independent experts was brought together to examine the clotting issue further six cases have been identified and j. and j. indicated. A possible seventh is being investigated. One person has died at the end of the meeting. The experts declined to vote on whether or not use of the. Jj vaccine should resume. Many members of the committee said they had too little information to be able to estimate the benefits and risks of the vaccine or to recommend. Its use be restricted to people in certain age groups that means the j. vaccine pause is likely to continue for at least another week to ten days while more data are gathered and analyzed joining us to help better understand this clotting issue and its implications for the jay vaccine. Both here in the. Us and abroad is k. Cup for schmidt. He's a science journalist and contributing correspondent to science magazine based in berlin germany. Kyw welcome to the podcast in q. So you've done some excellent reporting in recent days about the possible link between this rare clotting disorder observed and certain covid nineteen vaccines namely the astrazeneca vaccine. And now possibly the j. j. vaccine so you know based on the reporting you've done what appears to be happening biologically in these cases. Yeah that's that's a really difficult question. I mean First of all. I should say that you know all of this reporting has been done with my colleague rich vogel also also here in berlin and basically i think the phase that we're in is one where we're slowly going through different hypotheses and to shoot them down one by one in terms of what might be causing this now. One of the first things. I think you have to realize is what we do know. Is that these patients who have these rare complications seemed to have. Antibodies against platelet factor. Four and this is something that is very similar to a disease that we know heparin and use promo side opinion t and that's kind of the starting point for a lot of these scientists investigating what might be happening now in heparin induced thrombosis subpoena. You get these. Ps four antibodies. Because the ps four is a small molecule. That's positively charged. Heparin is a large molecule. that's negatively charged. And the idea. Is that in some patients when they get heparin the peer four binds to the heparin. And that makes it. More visible to the immune system and so the immune system starts producing antibodies against pia four. That leads to the plates being cross linked and activated. And so you get this clotting. That's what kind of stocks this the big question now is how does a vaccine in the absence of heparin produce. This picture and the first basic idea was well. We do know that in covid. Nineteen people sometimes have blood clots and possibly that has to do with spike protein. So maybe all that's happening. Is that the body sees. The spike protein produces antibodies against it and these antibodies just happened to also recognize. Ps four. because there's maybe some similarities there this hypothesis that was actually tested. It's just a preprinted at the moment but basically the researchers didn't see this as happening so it didn't see that for instance. The antibodies from people who had had covid nineteen recognized. Pia for now. There's a few other hypotheses. One that i find interesting is that maybe the dna that is being shuttled into cells from the through the edina virus in astrazeneca. For instance. Maybe that acts like heparin. Because dna to is large molecule that's negatively charged. And and the question there is. Is there really any free. Dna in in the vaccine normally it should be contained within the edina viruses. But of course. I think fifty billion particles in one dose of the vaccine so possibly some of those break open and then you have some of this negatively charged dna and possibly be. That's what leads to this again. It's just officers at the moment. People have some really interesting different ideas. About what would be causing it. And in some ways the johnson and johnson signal. We're seeing now and questions about the other vaccines that use. Said you know. Virus will be one part of the because it might help us to understand. Okay is it. The vector is it something else in these vaccines so the more we can tease apart which vaccines are causing this. Which vaccines aren't it. It gives us clues as to what the mechanism can be and what it can be. Is there a group that's been identified to be at higher risk of these unique clots. And does that perhaps say anything about the biological underpinnings of what's going on right. I mean that's been the debate in europe for a few weeks now because we did see a lot more of these rare clotting cases in women but then one of the big problems here was that it wasn't quite clear how many men and women were vaccinated with astrazeneca in the first place. So because of the way that the recommendations were at first in europe it was actually quite a lot of women. So i think was norway. For instance had five cases four of them women and one of them was a man and when they looked at who they actually vaccinated they found that they vaccinated exactly eighty percent of women and twenty percent men with astrazeneca so so that was exactly in line with that now in the.