What is ‘CVST’ – the extremely rare blood clot that’s affected 5 Brits after AZ jab?
A RARE type of blood clot has been reported in some people who have received the AstraZeneca Covid vaccine. Investigations into the cases are ongoing, but currently there is currently no proof that the blood clots were caused by the jab. The blood clot is called a cerebral venous sinus thrombosis (CVST). According to the […]
A RARE type of blood clot has been reported in some people who have received the AstraZeneca Covid vaccine.
Investigations into the cases are ongoing, but currently there is currently no proof that the blood clots were caused by the jab.
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The blood clot is called a cerebral venous sinus thrombosis (CVST).
According to the European Medicines Agency (EMA), 18 cases of CVST have been reported in 20 million people to have the vaccine.
Five cases have been reported in the UK of around 11 million AstraZeneca (AZ) vaccines, according to the Medicines and Healthcare products Regulatory Agency (MHRA).
There have also been two cases of CVST in people who had been given the Pfizer vaccine. One was very old.
Medics said the conditions were “extremely rare”, but can occur naturally.
The EMA said it had concluded the AZ vaccine is “safe and effective” and the benefits of preventing Covid deaths and hospitalisations outweigh any possible risks.
They added there was not an “overall increased risk” in blood clotting conditions, leading EU nations to perform a major U-turn after blocking the jabs for up to a week.
Here is everything you need to know about the condition.
What is CVST?
CVST is a serious condition which occurs when a blood clot forms in the brain’s venous sinuses.
This prevents blood from draining out of the brain and as a result, blood cells may break and leak into brain tissues, forming a hemorrhage.
This chain of events is part of a stroke, according to the John Hopkins University.
What are the symptoms?
The symptoms to look out for are a headache, blurred vision, fainting or loss of consciousness, loss of control over the body and seizures.
Anyone with a headache that lasts for more than four days after vaccination, or bruising beyond the site of vaccination after a few days, should seek medical attention.
Dr June Raine, MHRA chief executive, said this was a precautionary measure while investigations were ongoing.
How many people have had it after a vaccine?
The EMA said in a statement yesterday that there had been 18 cases of CVST reported in 20 million people to have the AstraZeneca vaccine.
It’s unclear exactly where these cases were.
The cases were linked with low levels of blood platelets – called thrombocytopenia – a symptom of which is excessive bruising.
Five of these cases were in the UK.
Dr Phil Bryan, MHRA vaccine safety lead, said: “This is extremely rare. So far, less than one in a million cases of this particular event after vaccination.”
It’s so rare that Dr Bryan said there was an issue with working out how common the combination of CVST and thrombocytopenia was.
Germany halted its use of the AZ vaccine after six cases of CVST with thrombocytopenia in 1.6 million people who had the jab.
In an update from the country’s health officials on March 16, experts said they saw “a striking accumulation of a special form of very rare cerebral vein thrombosis (sinus vein thrombosis) in connection with a deficiency of blood platelets (thrombocytopenia)”.
All cases were in younger to middle-age women.
Asked why the reports appeared to be so much higher in Germany, given that it has vaccinated considerably less people than the UK, the EMA said it was likely due to differences in the nations’ vaccine rollout target groups.
How many people does CVST affect usually?
Experts say CVST affects about five people in one million each year, according to John Hopkins University.
Paul Hunter, a professor of medicine at The Norwich School of Medicine, University of East Anglia, said studies have recently shown that CVST is “more common than previously thought” – around 13 to 15 cases per million.
This might suggest that the cases seen in those vaccinated is not actually higher than in the normal population.
However, it is the cluster of cases being reported in a short period of time, about one month, that has raised suspicions.
The condition has a number of risk factors in both adults and children, including obesity, pregnancy, cancer and inflammatory bowel diseases such as Crohn’s.
A report in the British Medical Journal (BMJ) said “the oral contraceptive pill appears to be an important additional risk factor”.
Doctors say stroke can be prevented by living as much of a healthy lifestyle as possible, such as by stopping smoking.
Were they caused by the vaccine?
THe EMA said it “cannot rule out” that the cases of CVST across Europe were caused by the AZ vaccine because there is not “sufficient evidence” either way.
Therefore, it said they will focus on raising awareness of the symptoms of the rare condition and make sure patient leaflets explain the case reports.
Similarly the MHRA admitted it “we don’t know whether these cases have been caused by the vaccine” – but that it was gathering more information to determine this.
Professor Sir Munir Pirmohamed, chairman of the expert working group of the Independent Commission on Human Medicines, said even if they found the vaccines did cause the spate of blood clots, it would not be necessary to stop giving the life-saving jabs.
He added there was a possibility the blood clots could have been caused by Covid itself either previously or close to the time of vaccination.
Both CVST and low blood platelets had been seen in Covid patients, Sir Munir said.
Can CVST be treated?
CVST needs immediate treatment.
It can cause death, but up to 86 per cent of patients have survive and have some kind of recovery, according to the BMJ report.
One of the five people to have suffered CVST after the AZ vaccine has died. But it is not clear if they had other underlying health conditions.
Like any stroke, CVST can lead to life-long complications, such as imparied speech or problems with vision.
What other blood clots are linked to the AZ vaccine?
The EMA also said it had seen a few cases of a condition called disseminated intravascular coagulation.
Seven cases in 20 million people given the AstraZeneca jab had developed this condition alongside low platelets.
The condition causes small blood clots to develop throughout the body, blocking small vessels and cutting off supply to organs such as the liver.
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Dr Sabine Straus, chair of PRAC – the safety committee of the EMA – said: “Tiny clots developed in multiple blood vessels in the first 7-14 days after vaccination.”
The symptoms of this condition include chest pain, shortness of breath, leg pain, problems speaking, or problems moving parts of the body.
The excessive clotting is usually stimulated by a substance that enters the blood as part of a disease or as a complication of childbirth or surgery.