A study published in The BMJ showed that people suffering from SARS-CoV-2, the virus that causes COVID-19, have an increased risk of developing blood clots for up to six months after the infection.
Researchers found that deep vein thrombosis, pulmonary embolism, and bleeding occurred up to two and six months after COVID-19 infection, respectively.
Additionally, patients with underlying conditions, patients with severe COVID-19, as well as those in the first wave of the pandemic compared to those in the second and third waves, have a higher chance of having events.
Researchers at Umea University in Sweden concluded that these results support measures targeted at preventing thrombotic events, particularly in high-risk patients, and emphasize the need for vaccination against COVID-19.
Between February 1, 2020 and May 25, 2021, more than one million people with confirmed SARSCoV-2 infection in Sweden were matched by age, gender, and county of residence to more than four million people who had not yet tested positive for SARS-CoV-2
The researchers first calculated the rates of deep vein thrombosis, pulmonary embolism, and bleeding in COVID-19 individuals during a control period, which was before and after the diagnosis of COVID-19. They then tested the rates at different time intervals following diagnosis of COVID-19 in order to compare them.
Following diagnosis of the COVID-19, they calculated the rate of deep vein thrombosis, pulmonary embolism, and bleeding 1-30 days later in the COVID-19 group and compared it to the control group.
In the study, the risk for deep vein thrombosis was significantly increased 90 days after COVID-19 compared to the control period, the risk for pulmonary embolism was significantly increased 180 days after COVID-19, and the risk for bleeding was significantly increased 60 days after COVID-19.
Researchers examined a range of potentially influential factors, and found a five-fold increase in deep vein thrombosis, a 33-fold increase in pulmonary embolism, and an almost twofold increase in bleeding risk in the 30 days following infection.
According to the researchers, 401 patients with the COVID-19 syndrome experienced their first deep vein thrombosis, while 267 control patients did not.