Dr K K Aggarwal
President CMAAO, HCFI,
With input from Dr Monica Vasudev
1564: 1. The risk of developing cerebral venous thrombosis (CVT) from COVID-19 is many-fold higher than from receiving the AstraZeneca/Oxford or the mRNA vaccines from Pfizer and Moderna.
2. A preprint study by the University of Oxford found that from a dataset of over 500,000 COVID patients, CVT would have occurred in 39 per million people.
3. CVT has been reported to occur in about 5 per million people after a first dose of the AstraZeneca/Oxford vaccine.
4. In over 480,000 people receiving either the Pfizer/BioNTech or Moderna mRNA vaccines, CVT occurred in 4 per million.
5. Compared to the mRNA vaccines, the risk of CVT from COVID-19 was about 10 times greater.
6. Compared to the Oxford vaccine, the risk of CVT from COVID-19 was about 8 times greater.
7. A similar pattern was seen in portal vein thrombosis (PVT) which occurred in 436.4 per million people who had COVID. That compared to 44.9 per million for the mRNA vaccine group, and 1.6 per million for those receiving the Oxford vaccine.
8. The major issue here is that the comparison showing the higher risk after COVID-19 does not exclude the possibility the pathogenesis is the same and therefore some common denominator should be searched.
9. For instance, if the mechanism is the same, one can speculate that the high occurrence in COVID-19 vs. vaccination is because the whole virus is more thrombogenic than the spike protein alone.
10. These studies are important but seem to be focused on demonstrating the minor risk of vaccination instead of making efforts to explain the cause of complications, taking advantage of the similarities of the events in the two populations.
