Whether these rare clotting events in Europe and the ITP cases in the U.S. bear anything in common is anyone’s guess right now.
One hypothesis is that the mRNA vaccines (Pfizer, Moderna) and those using adenoviruses (AstraZeneca, Johnson & Johnson) could induce synthesis of the COVID spike protein within platelets, which may then trigger autoimmune reactions against platelets, Hamid Merchant, PhD, of the University of Huddersfield in England, wrote in a letter to The BMJ.
“COVID genetic vaccines may have a direct role in spurring an autoimmune response against platelets that may clinically manifest in thrombocytopenia, hemorrhage, and blood clots. Clotting risks may be equally possible with all genetic COVID vaccines, and may not be limited only with the AstraZeneca/Oxford vaccine,” he told MedPage Today .
that letter also says:
There have been over 150 reports of post-CoViD19 vaccination thrombocytopenia recorded in the pharmacovigilance databases at VAERS [5] and MHRA [6], and at least one confirmed death in USA which is still under investigation [7]. ITP have also been previously reported with a number of other vaccines, such as flu, poliomyelitis, pneumococcal, hepatitis, MMR, and rabies. The vaccine mediated autoimmunity was proposed to be associated with both the antigen and vaccine constituents, for instance the trace proteins from the culture media (such as yeast proteins), adjuvants, preservatives, or formulation carriers
When this story first broke there were a couple of labs that said they had discovered a plausible mechanism for the clotting. I wouldn’t be surprised if this was it.
Since covid causes clotting, and a lot of the worst effects seem linked to an whacky immune response, it seems incredibly plausible that the vaccine could cause clotting. That it seems to be an incredibly rare outcome is quite reassuring.
Thanks – I just realized I can access the BMJ letter itself, which has that info. And a pharmacy degree is worth paying attention to in this context. Just checking in light of some of the self-annointed “experts” that sometimes like to spout theories. Thanks for posting this, and for the follow-up.
Dr Merchant has a Pharmacy degree (BPharm) with a Masters in Pharmaceutics (MPharm) from University of Karachi and a PhD in Clinical Pharmaceutics from the University College London (UCL). He also have a PGD in Quality Management from NED and a PGCert in Higher Education from Huddersfield.
He has over 18 years of experience in pharmaceutical research and development both from industry and academia. His expertise includes novel formulation design, biopharmaceutics, pharmacokinetics, bioavailability and bioequivalence. He has a particular interest in drug delivery research at the interface of gastroenterology and publishes regularly in peer-reviewed journals
I finally went and read the letter and I just wanted to put his final paragraph here for lay people to see how a scientist provides conclusions (in case you don’t know from reading it, it is exactly right for a scientific journal).
In authors opinion, it is plausible that CoViD genetic vaccines may have a direct role in spurring autoimmune response against platelets that may clinically manifest in thrombocytopenia, haemorrhage, and blood clots. It, however, requires substantial evidence to confirm this hypothesis. Vaccines are one of the great discoveries in medicine that has improved life expectancy dramatically. Nonetheless, genetic vaccines are new, and their long-term safety evaluation is a key to identify potentially contraindicated group of subjects, for instance patients with history of blood disorders, past or current thrombocytopenia or pre-existing immunological conditions. European Medicines Agency (EMA) continues to investigate the recent thrombotic events in Europe, and we shall look forward to their findings.
Well, based on the expertise listed I have to disagree.
novel formulation design - self explanatory; designing viable systems for delivering medicines
biopharmaceutics - " Biopharmaceutics examines the interrelationship of the physical/chemical properties of the drug, the dosage form (drug product) in which the drug is given, and the route of administration on the rate and extent of systemic drug absorption." Source.
pharmacokinetics - essentially the absorption, distribution, metabolism and excretion of drugs
bioavailability - systemic availability of a drug from the dosage form
bioequivalence - the equivalence, in terms of bioavailability, of dosage forms.
That’s a guy well positioned to be developing generic drugs. How this qualifies him to have an opinion on autoimmune responses triggered by vaccines, and the mechanisms involved - well, I’m not seeing that. (Back in the day my CV wasn’t that different; but don’t ask me to figure this particular problem out, please!)
Incidentally, as a public service to readers of that publication, megakaryocytes are blood cell precursor cells; they are acted on by interleukins, which cause them to commit to production of a particular blood cell type - in this discussion, platelets. The letter is suggesting that the cause of the thrombocytopenia (low platelet count) is in part an autoimmune response affecting megakaryocytes, thus cutting off platelet supply upstream, as it were.
(There’s something dredged from memory that I never thought I’d use again!)
The European Medicines Agency stressed that the benefits of vaccination still outweigh the risks, as thousands of people die of coronavirus across the continent each day. But British officials advised that adults under 30 be offered alternative vaccines, noting that the calculus is different for young and otherwise healthy people who are at relatively low risk of serious covid-19.
The new guidelines marked a notable shift for the United Kingdom, where the government has wholeheartedly backed its homegrown vaccine even as other European countries raised concerns. Even some members of the country’s scientific community had initially derided European pauses to vaccination due to safety concerns as politically motivated.
“This is a course correction,” acknowledged Jonathan Van-Tam, England’s deputy chief medical officer, in a televised briefing.
As the WaPo article is part-paywalled, here’s the story from the BBC:
(Which referred to numbers revised upwards from 5 to 30. Now revised upwards again - see next quote. A very prescient observation.)
The offer of an alternative vaccine for under 30s applies to the UK. As I haven’t read the WaPo article, I don’t know if it gives numbers, but here are the (latest) numbers from the BBC article (my bold).
The recommendation comes after a review by the UK drugs regulator found that by the end of March 79 people had suffered rare blood clots after vaccination - 19 of whom had died.
The regulator said this was not proof the jab had caused the clots.
But it said the link was getting firmer.
Every time this story comes back, more cases have been found. As I said (my added bold):
I fear that the full picture may still be emerging. This has been a woeful episode for the MHRA.
The WaPo article has lots of numbers. Thanks for finding a non-paywalled link.
The article goes a little bit into the new calculations being done to compare the risk of blood clots to the risk of severe Covid for younger age groups. If I understand correctly, it says for those in their 20s, the risk from the vaccine would be considered greater.
It also says that the spike protein is not suspected to be the cause, but the viral vector is suspected. And that clinicians should be able to test for the antibodies they suspect are the cause. Johnson & Johnson uses a similar technology, so some scrutiny will be coming to that vaccine.
Peter Arlett, head of pharmacovigilance at the EMA said that J&J’s vaccine “uses a similar technology” and there have been three cases of blood clots accompanied by low platelet counts among recipients of that vaccine that “have some similarities” to those seen as a result of AstraZeneca.
I wonder if that number – three so far – will be changing now that the complication is being looked for. I hope not – I hope this is limited to the Astra Zeneca vaccine.
I heard a reporter today claiming all the instances of clotting occurred to people after their first jab and therefore people waiting for their second jab should not worry. I’m not sure about that logic and I cannot find any where else that claims or suggests this.
All the recorded cases occurred after the first dose, although the lower number of second doses meant it was not possible to draw any conclusions from this
I remember hearing on the radio (I think it was NPR) that one group from Germany noted that besides being a rare reaction, they reported that it should not be hard to identify the ones at risk with the rare antibodies that cause the bad reaction, they also noted that if one is alerted to the early side effects of this bad reaction anyone that gets the symptoms and gets prompt care the clotting can be minimized with known medicines.
I think this was the group, but the article here does not mention the more reassuring tone that the radio report gave.
Now I suppose we know the answer to this question. I would think that the trial will be outright stopped unless some way is found to drastically reduce the risk of clots. Kids are at very low risk from Covid, so having to wait for a different vaccine is presumably very low risk, and other vaccines without that safety concern are being studied for kids.