A study of nearly 30 million people in England who’ve received either the Oxford/AstraZeneca or the BioNTech/Pfizer vaccine indicates that the risk of blood clots after contracting coronavirus is many times larger than the risk presented by either vaccine.
The results of the study, published in the British Medical Journal Friday, found that the Oxford/AstraZeneca vaccine is tied to an increased risk of low platelets and blood clots in veins. For the BioNTech/Pfizer vaccine, there’s an increased risk of an ischaemic stroke and blood clots in arteries.
Aziz Sheikh, professor of primary care research & development at the University of Edinburgh, drove home the point in a briefing that the risk is considerably higher if someone contracted the virus. For example, the risk of low platelets (thrombocytopenia) is nearly nine times higher with a COVID-19 infection than with the Oxford/AstraZeneca vaccine in the eight to 28 days post-vaccination. That’s comparable to the risk from a flu vaccine, he said.
In cases of ischemic stroke, the risk is nearly 12 times higher after a COVID-19 infection than after the BioNTech/Pfizer jab.
This effort is the largest study to look at this question, and unlike other studies that often look at only one vaccine, these researchers compared two jabs side by side. Peter English, a retired consultant in communicable disease control and former editor of Vaccines in Practice, described the study as “very important.”
The report comes on the heels of a study published in the New England Journal of Medicine this week using Israeli data on the rollout of the BioNTech/Pfizer vaccine. It found that while the vaccine increased the risk of heart inflammation, the risk was higher among those infected with the virus.