Seven people died of rare blood clots after receiving the Oxford-AstraZeneca vaccine in the United Kingdom, the British health surveillance agency confirmed to the BBC.
In total, 30 of the 18 million people vaccinated by March 24 in the country developed these clots.
It is not yet clear whether they are just a coincidence or a side effect of the immunizer.
But the Medicines and Health Products Regulatory Agency (MHRA), a British government body equivalent to Anvisa (Health Surveillance Agency) in Brazil, says the benefits continue to outweigh any risk.
Still, the concern has led other countries, including Germany, France, the Netherlands and Canada, to restrict the use of the vaccine to older people only.
In Brazil, the Oxford-AstraZeneca vaccine is one of the immunizers approved for use by Anvisa.
The data released by the MHRA on Friday (2/4) showed 22 cases of cerebral venous thrombosis (CVT), which is a type of blood clot in the brain.
These were accompanied by low levels of platelets, which help to form blood clots in the body. MHRA also found other clotting problems along with low levels of platelets in eight people.
The agency confirmed, in an email sent to the BBC, that “unfortunately seven (people) died”.
June Raine, executive director of MHRA, said: “The benefits … in preventing covid-19 infection and its complications continue to outweigh any risks and the public must continue to receive their vaccine when asked to do so. “
Investigations are now underway to determine whether the AstraZeneca vaccine is linked to the formation of these rare blood clots. Earlier this week, the European Medicines Agency said that relationship “has not been proven, but it is possible”.
Two issues are raising suspicions. The first is the unusual nature of clots, which include low levels of platelets and rare antibodies in the blood that have been associated with other clotting disorders.
“This raises the possibility that the vaccine could be a causative factor in these rare and unusual cases of CVT, although we don’t know it yet, so more research is urgently needed,” said David Werring, from the Institute of Neurology at University College London ( England).
The other issue is the difference between the Oxford-AstraZeneca and Pfizer-BioNTech vaccines.
There were two cases of CVT following the administration of the Pfizer immunizer in the UK, out of more than 10 million vaccinees, but these did not have low platelet levels.
However, uncertainty remains about how common these clots are normally. Estimates range from two cases per million people each year to almost 16 out of every million in normal times, and the coronavirus has been associated with abnormal clotting, which may be making these clots more common.
Germany reported 31 TVCs and nine deaths in 2.7 million vaccinated people in the country, with the majority of cases in young or middle-aged women.
Similar data on who was affected in the UK has not been published locally, but people of different genders and age groups are believed to have been affected.
One scientist told the BBC that there is growing evidence that blood clot events are “causally related”, although he emphasizes that the benefits of taking the AstraZeneca vaccine still outweigh the risks of not receiving the immunizer.
Paul Hunter, professor of medicine at the University of East Anglia (England), told the BBC: “It is not uncommon to obtain groups of rare events purely by chance”.
“But once you find that cluster in one population and it appears in another – as previously in Germany and now in the UK – then I believe that the chances of it being a random association are very, very low.”
“Clearly, more studies are needed, but I think the evidence is shifting more towards proving this causal relationship at the moment.”
However, public health specialist Linda Bauld of the University of Edinburgh (Scotland) told the BBC that the cases were “rare events” and emphasized that there were no events “at the time of a causal relationship – that the vaccine would be causing these results directly. “
She recommended that the public continue to introduce themselves to get the vaccine and added: “Covid itself increases the risk of blood clots quite significantly and it is possible that this is part of the explanation of why we are seeing this.”
All medications, from vaccines to paracetamol, have the potential to cause serious side effects.
The seasonal flu vaccine has about a one in one million chance of causing Guillain-Barré syndrome.
So the real question is, do the risks outweigh the benefits?
Even though the vaccine was the cause, and this has not yet been proven, the numbers point to around one death for every 2.5 million people vaccinated.
However, this must be weighed against the known threat posed by the coronavirus.
If 2.5 million 60-year-olds caught the coronavirus, about 50,000 would die. If everyone were 40, about 2,500 would die.
This balance of risk and benefit will be better assessed as more data is revealed and more young people, who are less at risk of dying from covid-19, are vaccinated.
You’ve already watched our new videos on YouTube? Subscribe to our channel!
Get the latest news delivered to your inbox
Follow us on social media networks