Study finds Covid-19 linked to increased risk of blood clotting

Covid-19 at any level of severity is linked to an increased risk of dangerous blood clots that start in patients’ veins and travel to the heart, lungs and other parts of the body, according to a UK study that highlights the pandemic’s role in driving up rates of cardiovascular disease.

Non-hospitalized Covid patients were 2.7 times more likely to develop dangerous clots called venous thromboembolisms and were more than 10 times more likely to die than individuals who avoided the disease, scientists at Queen Mary University of London found in a study of almost 54,000 people followed for an average of about 4 1/2 months. The increase in risk was highest in the first 30 days after the disease began, but could remain elevated even longer, the researchers said.

The findings are yet another sign of the hidden dangers of the virus that can result even from mild cases. Yet risks were significantly worse for patients hospitalized for Covid, who had 28 times higher risk of venous thromboembolism, 22 times increased risk of heart failure and 18 times greater risk of stroke than unaffected people. Their chance of dying was 118-fold higher compared with their uninfected counterparts.

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The research, based on data collected during the country’s first two Covid waves from participants in the UK Biobank study, was published Monday in the journal Heart. It adds to evidence of Covid’s propensity to damage blood vessels and cause life-threatening clots, especially early in the infection.

“Our findings highlight the increased cardiovascular risk of individuals with past infection, which are likely to be greater in countries with limited access to vaccination and thus greater population exposure to Covid-19,” Zahra Raisi-Estabragh, a clinical research training fellow at Queen Mary, and co-authors wrote. “Further research is required to delineate the period over which the augmented cardiovascular risk persists.”

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The “astronomically” increased risk of death among non-hospitalized Covid patients is “another reminder that, although many countries seem to have normalized getting Covid infection, there is nothing about Covid that is normal,” said Ziyad Al-Aly, chief of research and development at the Veterans Affairs St. Louis Health Care System.

“We cannot truly make our way out of this pandemic without an exit strategy that blocks transmission and outpaces the ever changing variants of this virus,” Al-Aly, whose own studies have led to important early findings about Covid’s health effects, said in an email. “We urgently need a variant-proof strategy and vaccines that reduce transmission.”