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In one of the largest studies of its kind to date, researchers found strong evidence that heart attack and stroke risk rises sharply in the weeks following a COVID-19 diagnosis. The findings were published Aug. 14, 2021, in The Lancet.
The study included every person in Sweden diagnosed with COVID-19 from Feb. 1, 2020, to Sept. 14, 2020 — a total of nearly 87,000 people. Their median age was 48, and 57% were women. Researchers compared them with more than 348,000 Swedish people of similar age and sex who did not have the virus.
In the week after a COVID-19 diagnosis, the risk of a first heart attack increased by three to eight times. The risk of a first stroke caused by a blood clot multiplied by three to six times. In the following weeks, both risks decreased steadily but stayed elevated for at least a month.
Other bacterial and viral infections (such as influenza) are known to temporarily boost rates of heart attacks and strokes. But COVID-19 infections appear to be especially risky, perhaps because they trigger an exaggerated inflammatory response that makes blood clots more likely.
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