London: Amid growing concerns over vaccines vis-a-vis blood clots, researchers at Oxford University found that the risk of developing a clot is higher for people infected with COVID-19 than those who haven’t. They also pointed out that overall, the risk is extremely low.
All 3 vaccines approved in the UK — Oxford-AstraZeneca, Moderna and Pfizer — were taken into consideration.
The study said that the risk of cerebral venous thrombosis or CVT following COVID-19 infection is around “100 times greater than normal and several times higher than it is post-vaccination or following influenza” for all age groups.
Even the World Health Organization (WHO) on April 15 had stated that the risk of suffering blood clots is much higher for someone with COVID-19 than for someone who has taken the AstraZeneca vaccine. The WHO has also said that the AstraZeneca vaccine is “effective in reducing COVID-19 hospitalization and preventing deaths.”
The researchers at Oxford University examined the number of CVT cases diagnosed within two weeks of taking the first dose of vaccine. They compared this to incidences of CVT following influenza.
They found that CVT is more common after COVID-19 than in any of the groups. The risk with mRNA vaccines is about 10 times higher and that of AstraZeneca is about 8 times higher.
The researchers concluded that COVID-19 markedly increases the risk of CVT caused due to blood clots.
Recently, Johnson & Johnson’s single dose vaccine was paused by US authorities following a blood clot in a woman that led to her death.