University study of COVID-19 vaccines rebuts fears of blood clots


A University of Oxford study has indicated people are more likely to develop a blood clot after being infected by COVID-19 than they are after receiving a single dose of the AstraZeneca or Pfizer (NYSE:PFE) vaccines.

In other words, people holding off from having a jab because of concerns about the heightened risk of developing a blood clot are probably making a poor decision, although the study did conclude that there is a heightened chance – albeit minute – chance of developing a blood clot after receiving either the AstraZeneca or Pfizer (NYSE:PFE) vaccine.

The study also concluded there is an increased risk of stroke after receiving the Pfizer (NYSE:PFE) jab but as with the blood clot risk, the probability of suffering a stroke after being infected with the coronavirus is higher.

The research team studied records of more than 29mln people who received the first dose of a COVID-19 vaccine between December and April, and the records of almost 1.8mln people who had been infected with the virus.

The results of the study indicated that while 107 people in every 10mln would be hospitalised or die from a low blood platelet count after receiving the AstraZeneca jab, almost nine times as many people would suffer the same condition following a COVID-19 infection.

Furthermore, for every 10mln people vaccinated with the AstraZeneca vaccine, 66 would be hospitalised or die from blood clots in the veins but around 200 times more people would suffer the same fate after being infected with the coronavirus.

As for the Pfizer vaccine, the numbers (per 10mln) indicated an infection was 12 times more likely to cause a stroke than the jab.

“People should be aware of these increased risks after COVID-19 vaccination and seek medical attention promptly if they develop symptoms, but also be aware that the risks are considerably higher and over longer periods of time if they become infected with SARS-CoV-2,” said Julia Hippisley-Cox, professor of clinical epidemiology and general practice at the University of Oxford.

“This research is important as many other studies, while useful, have been limited by small numbers and potential biases. Electronic healthcare records, which contain detailed recording of vaccinations, infections, outcomes and confounders, have provided us with a rich source of data with which to perform a robust evaluation of these vaccines, and compare to risks associated with COVID-19 infection,” she added.


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