Vaccines may increase brain vein clots in severe COVID-19

Vaccines may increase brain vein clots in severe COVID-19

Note that views expressed in this opinion article are the writer’s personal views and not necessarily those of TrialSite.

Dr. Ron Brown

June 9, 2021

A June 8, 2021 article in Medpagetoday.com claims that brain vein clots are less likely with vaccines than with severe COVID. Brain Vein Clots Less Likely With Vaccine Than With Severe COVID | MedPage Today. Stated another way, incidence of brain vein clots (cerebral venous sinus thrombosis – CVST) is higher in severely ill people with COVID-19 than in otherwise healthy people who develop brain vein clots as an adverse effect of COVID-19 vaccines (vaccine-induced thrombotic thrombocytopenia – VITT). Although there is nothing particularly astonishing about comparing blood clot outcomes in groups of seriously ill and healthy people, the author of the Medpagetoday.com article appears to draw a misleading conclusion about vaccine risk-benefits from these data. The author’s interpretation seems to be that people who wish to avoid brain vein clots have a better chance of protection if they are vaccinated, even with the potentially small risk of brain vein clots from the vaccine. The logic is clear: vaccines prevent COVID-19, and so you are at less risk of VITT from the vaccine than you are if you avoid the vaccine altogether and develop severe COVID-19 associated with CVST. But in reality, the opposite is true.

The false assumption on which the author’s conclusion is based is that vaccines prevent COVID-19. For example, the public has been told that vaccine efficacy in the Pfzier/BioNTech and Moderna COVID-19 vaccine clinical trials are 95.1% and 94.1%, respectively. Medicina | Free Full-Text | Outcome Reporting Bias in COVID-19 mRNA Vaccine Clinical Trials (mdpi.com). Based on these too-good-to-be-true relative risk reduction measures alone, the author’s risk-benefits analysis of vaccine protection against blood clots seem valid. But, the FDA points out that absolute risk reduction measures should also be reported to the public, which for the Pfzier/BioNTech and Moderna vaccines is a mere 0.7% and 1.1% respectively, indicating hardly any vaccine clinical impact on COVID-19 prevention. These absolute risk reduction measurements remain clinically valid, regardless of the length of time of the clinical trials. Response to Argument Against COVID-19 Vaccine Absolute Risk Reductions (trialsitenews.com). Furthermore, the vaccine clinical trials’ endpoint was a positive infection with a mild or moderate clinical symptom. There is no causative trial evidence that the vaccines prevent severe illness, hospitalizations, or deaths in otherwise healthy people.

In conclusion, COVID-19 vaccines potentially add an increased risk of vaccine-induced brain vein clots, VITT, without any causative trial evidence of preventing severe COVID-19 and the associated risk of brain vein clots, CVST.

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