As we know, the FDA has halted the use of the Johnson & Johnson vaccine due to the risk of blood clots. This issue is becoming more complex, as evidence is showing that both the Moderna and Pfizer products cause many times more clots than AstraZeneca’s not-yet-US-approved vaccine, which in turn is facing the same blood clot issues as J&J. And a separate issue, the fact that catching COVID-19 will raise your clot risk more than any vaccine, is being headlined by Oxford University in their April 15 discussion of these issues. They note that researchers at that institution have reported that the risk of the clotting known as CVT, or cerebral venous thrombosis, among COVID-19 patients is about 10 times higher than among the vaccinated and about 100 times higher than the risk of this disorder in the general public. Oxford quotes one researcher, “We’ve reached two important conclusions. Firstly, COVID-19 markedly increases the risk of CVT, adding to the list of blood clotting problems this infection causes. Secondly, the COVID-19 risk is higher than we see with the current vaccines, even for those under 30; something that should be taken into account when considering the balances between risks and benefits for vaccination.”
Comparable Clot Rates with Moderna and Pfizer; Firms Declined to Help J&J
MarketWatch reported on April 15 that, “Blood clots as prevalent with Pfizer and Moderna vaccine as with AstraZeneca’s: study.” Citing a study from Oxford University they note that the rate of blood clots is about the same for Moderna and Pfiizer mRNA products as it is for the troubled AstraZenena vaccine. Per the study, about 4 in a million folks get cerebreal venous thrombosis after getting one of the mRNA vaccines, and about 5 in a million get CVT after the AstraZeneca vaccine. MarketWatch focused on CVT, but there have also been reports of PVT, or portal venous thrombosis. One (albeit sensationalistic) outlet that has looked at this issue is RT, who offered their take on the blood clot question on April 16. They offer that the Oxford data shows that blood clotting disease is 30 times more common in those who have gotten Moderna or Pfizer products than those “given the troubled AstraZeneca jab”. Looking at clotting in the portal and/or abdominal veins, splanchnic thrombosis or PVT, they found an incidence of 1.6 per million for the AstraZeneca vaccine and 44.9 per million for those who had used an mRNA vaccine by Moderna or Pfizer. As to CVT, incidences were 4.1 per million for those who had an mRNA product and 5.0 per million for those who had the AZ vaccine. ABC News has compared the clotting from J&J’s vaccine versus that from AstraZeneca. “The AstraZeneca and Johnson & Johnson vaccines are made in a similar way,” opined Dr. William Schaffner, infectious disease physician at Vanderbilt University with further expertise in preventive medicine and policy. “But the carriers are different kinds of adenoviruses … that’s part of the background information, why indeed there is a pause now.”
Dr. Richard Kuhn, Purdue University virus expert, notes, “It’s hard to say if it’s the same problem—but it does seem the vaccine triggers an antibody response that activates platelets, leading to clots.” On a final note, as reported by CNBC, J&J had privately asked rivals Moderna and Pfizer to join in a study looking at blood clot risks, but the two firms declined. Per news reports, “Executives at Pfizer and Moderna said their vaccines appeared safe and they didn’t see the need to duplicate the efforts of regulators and companies already looking into the rare blood clot issue.” AstraZeneca did accept the offer to partner on clot research.