Covid – unvaccinated – at greatest risk of blood clot: study

Covid - unvaccinated - at greatest risk of blood clot: study

A health worker cares for a COVID-19 patient in the intensive care unit at Robert Bosch Hospital in Stuttgart, Germany on Tuesday, January 12, 2021.

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A new study has found that the risk of rare blood clots forming as a result of catching COVID-19 is significantly higher than when vaccinated against the virus.

In a peer-reviewed study published in the British Medical Journal on Friday, researchers from the University of Oxford, the London School of Hygiene and Tropical Medicine and several other UK universities and hospitals analyzed data from more than 29 million people who received their first dose. To see her. Either the Oxford-AstraZeneca vaccine or the Pfizer-BioNtech vaccine. The study authors were completely independent from the developers of the Oxford-AstraZeneca vaccine.

Scientists looked at the rates of thromboembolic events – blood clots – and thrombocytopenia, a disease characterized by a low platelet count. Rare blood clots with low platelet counts have been linked to the Oxford-AstraZeneca COVID-19 vaccination.

The article compared the rates of rare blood clots after the first dose of vaccination and after a positive COVID-19 test.

The researchers found that the risk of these adverse events following COVID-19 infection was “considerably higher” than after receiving the Oxford-AstraZeneca or Pfizer-BioNTech vaccines.


Eight to 28 days after the first dose of the Oxford-AstraZeneca vaccine, researchers identified an increased risk of rare blood clotting events and low platelet counts. During the same period after the first dose of Pfizer-BioEntech vaccine, the study found an increased risk of blood clots and stroke due to restriction of blood flow to the brain (ischemic stroke).

However, these risks were much lower than the risks posed by COVID-19 infection.

The researchers estimated that 107 of the 10 million people would be hospitalized or die from a low platelet count within 28 days of receiving the first dose of the Oxford-AstraZeneca vaccine. In contrast, the number rose to 934 for 10 million after testing positive for Covid-19.

Within 28 days of the first dose of the Oxford-AstraZeneca vaccine, 66 in 10 million people were hospitalized or died from blood clots in their veins, while 12,614 out of 10 million people tested positive for the virus. Has been tested.

Meanwhile, 143 out of 10 million people were hospitalized or died of ischemic stroke within 28 days of the first dose of Pfizer-BioNTech vaccine, while 1,699 people tested positive for COVID-19.

The study concluded that the risk persisted even longer after contracting the coronavirus after vaccination.

The study analyzed electronic health records collected regularly to assess the risk of hospitalization for blood clots and low platelet count within 28 days of infection or vaccination.

The data used in the study was collected between December 1, 2020 and April 24, 2021, across England. Patients who were in hospital at the end of the study were excluded from the study.

Vaccine trial ‘unlikely’ to detect very rare side effects

Researchers noted on Friday that all COVID-19 vaccines currently in use in the US and UK have been tested in randomized clinical trials, which should be large enough to detect very rare adverse events. There was no way.

When rare events are discovered, regulators perform risk-benefit analyzes to weigh the adverse effects against the benefits of receiving the vaccine, the study authors said.

The UK Joint Committee on Vaccination and Immunization has consistently said that the benefits of the Oxford-AstraZeneca vaccine outweigh the risks for the vast majority of people.

Several health authorities, including the WHO, the European Medicines Agency and the International Society for Thrombosis and Hemostasis, have also agreed that the benefits of vaccination outweigh the risks.

“People should be aware of these increased risks after a COVID-19 vaccination and seek immediate medical attention if they develop symptoms, but also be aware that there is a risk of getting infected with SARS-CoV-2. much longer and lasts longer. Julia Hippiesley-Cox, professor of clinical epidemiology and general medicine at the University of Oxford and lead author of the article, said in a press release.

“This massive study has shown that there is a very low risk of clotting and other blood disorders after the first dose of COVID-19 vaccination. Although serious, the risk of these similar results is much higher after infection with SARS-CoV-2, ”said Aziz. Sheikh, professor of primary care research and development at the University of Edinburgh and co-author of the article.

According to the UK government, visible symptoms include a new severe headache that is not relieved by common pain relievers, a headache that gets worse when lying down or bending over, unexplained bruising or bleeding, shortness of breath and legs. inflammation of



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