Catching COVID increases chances of blood clots for up to six months after infection
Those suffering from underlying health problems are most at risk
Last updated 29th May 2022
People who have caught COVID-19 could be at higher risk of developing blood clots by as late as six months after being infected, according to new research.
A study carried out by researchers at Umea University in Sweden, published in the British Medical Journal, found that the risk of having blood clots was "significantly increased" after contracting the virus.
As well as this, those with underlying health conditions were found to be most at risk of developing clots, as well as other problems including deep-vein thrombosis and bleeding.
The study was carried out during the course of the COVID-19 pandemic, from February 2020 to May 2021, which saw test results from one million positive cases plotted against four million negative cases.
In total, during the period of the study, 1,761 people who tested positive suffered a pulmonary embolism - a block blood vessel in the lungs - compared to just 171 patients who tested negative.
According to the study, the risk of developing the health problems was highest during the first wave of the pandemic in March 2020, with later waves posing less of a threat.
Researched suggested that this may be as a result of the global vaccination effort and as a result, more vulnerable groups such as the elderly would not be as susceptible.
In their conclusions, the researching team said: "Our findings arguably support preventative treatment to avoid thrombotic events, especially for high risk patients, and strengthen the importance of vaccination against Covid-19."
It comes as the number of people in the UK suffering from COVID-19 continues to surge, according to government figures.
The number of people in hospital with COVID-19 has also reached its highest level for 13 months, with around 20,400 people receiving treatment for the virus.
However, just over half of those in hospital with the virus are simultaneously being treated for other illnesses, up from a quarter in the summer of 2021.
Your questions on COVID-19 answered:
What is Covid-19?
Covid-19 emerged as a virus in December 2019 as the first cases are reported in Wuhan, China. Scientifically known as SARS-CoV-2, the virus created a global pandemic as it began to spread around the world. Symptoms can range from very mild to severe, causing death in some cases. Some people are completely asymptomatic and do not realise they even have the virus.
Has there been a virus like this before?
The SARS pandemic in 2003 was similar to Covid-19 in that it was also caused by a coronavirus. SARS stands for Severe Acute Respiratory Syndrome. The global outbreak of SARS lasted from 2002-2003, infecting over 8,000 people and killing 774. Covid-19 and SARS are both respiratory illnesses, but SARS was much more deadly and less infectious.
What are the main symptoms?
The NHS say the main Covid-19 symptoms are a high temperature, a new and continuous cough and loss or change to taste of sense or smell. NHS advises people with Covid-19 to take plenty of rest, drink lots of fluids, and take paracetamol for a high temperature.
What was the Government reaction?
The UK Government announced the first of several lockdowns in March 2020. By the end of the month, more than 100 countries around the world introduce full or partial lockdowns, preventing people from going to work, restricting everyday tasks and affecting the livelihoods of billions of people globally.
Which countries have been worst hit?
During the first year of the pandemic, the US recorded the highest number of Covid-19 cases in the world and the most deaths, reporting an unprecedented 100,000 new cases in one day on November 4th 2020. Thousands of new cases were recorded on the same date in India (46,000+), the United Kingdom (22,000+), Brazil (17,000+) and Mexico (5,000+), while Ireland records less than 1,000 (578). Hundreds of other countries also reported a high rate of infection.
How have vaccines fought against Covid-19?
Vaccines began being approved for use across the globe. By January 2021, the UK approved the use of three different vaccines. The Pfizer-BioNtech vaccine, Oxford/AstraZeneca vaccine and the Moderna vaccine are rolled out to the public, with older people and those with greater health concerns getting priority. In April 2022, just under 53 million people had received at least one dose of the vaccine.
What are new Covid variants?
Four new variants of Covid-19 were discovered around the world. Beta was found in South Africa, Gamma in Brazil and Delta in India, while the Alpha variant was first located in Kent, UK. New variants are not likely to make someone more seriously ill than Covid-19 would, but variants like Delta have a higher infection rate, meaning it can be more easily spread.
The Omicron variant was first detected late 2021 in South Africa. Since then, it has become one of the most dominant variants in the world, with its own sub strains - BA.4 and BA.5.