WE all know that coronavirus can leave some people with dreaded long Covid.
But now, researchers have discovered the bug can leave sufferers with a potentially deadly complication.
While relatively rare, British experts have warned Covid-19 increases the risk of life-threatening blood clots – for at least a year after infection.
Blood clots can cause heart attacks, strokes, pulmonary embolism (PE), deep vein thrombosis (DVT) and in worst cases, death.
The findings, published in Circulation, are based on an analysis of 48 million health records, found the virus may have led to an additional 10,500 heart attacks.
It’s also believed the virus caused several other blood clot complications such as DVT and PE in England and Wales alone.
DVT is a blood clot which often forms in the leg.
Whereas PE is a blood clot that blocks up a blood vessel in your lung.
Both conditions are serious and can lead to disability or even death.
People with mild or moderate forms of Covid were also affected, the researchers said.
However, the scientists from Universities across the UK, did point out that the blood clot risk to those who catch Covid is small and reduces over time.
The study authors suggested preventive strategies, such as giving high-risk patients medication to lower blood pressure, could help reduce cases of serious clots.
The research involved studying anonymised electronic health records across the whole population of England and Wales from January to December 2020.
They compared the risk of blood clots after Covid-19 with the risk at other times.
In the first week after a Covid-19 diagnosis, people were 21 times more likely to have a heart attack or stroke – conditions which are both caused by blood clots blocking arteries.
This risk then dropped to 3.9 times more likely after four weeks, researchers said.
Similarly, the risk of developing conditions caused by blood clots in the veins – including deep vein thrombosis and pulmonary embolism – also increased.
The risk of blood clots in the veins was 33 times greater in the first week after a Covid-19 diagnosis.
This dropped to eight times more likely after just one month.
Previous studies looked into the impact of Covid-19 on blood clotting in people hospitalised with the disease.
But this new research proves that even those who are not hospitalised are at risk of developing blood clots.
Although their risk is not as great as for those who had severe disease and were hospitalised.
What are the signs of a blood clot
Blood clots can be very serious and need to be treated quickly. Staying healthy and active can help prevent them.
Symptoms of a blood clot include:
- throbbing or cramping pain, swelling, redness and warmth in a leg or arm
- sudden breathlessness, sharp chest pain (may be worse when you breathe in) and a cough or coughing up blood
Those most at risk are men over the age of 80, with an extra two in every 100 infected having a stroke or heart attack after catching the bug.
Professor Jonathan Sterne, an epidemiologist at the University of Bristol, who co-led the study, said: “We are reassured that the risk drops quite quickly – particularly for heart attacks and strokes.
“But the finding that it remains elevated for some time highlights the longer-term effects of Covid-19 that we are only beginning to understand.”
Previous research has suggested that your risk of a deadly blood clot is higher if you don’t get the vaccine and catch Covid.
However, vaccines have been linked with cases of blood clotting in a tiny number of people since March, but are still deemed safe and effective.
Health chiefs have urged people to keep coming forward for their shots regardless of the tiny risk.