At least 30 people in the UK have developed unusual forms of blood clots since receiving the Oxford-AstraZeneca vaccine, according to the UK’s medicines regulator, although it’s too early to say if the shot caused the clots.
Out of a total of 15.8 million people who had received at least one dose of the vaccine by March 21, the Medicines and Healthcare Products Regulatory Agency (MHRA) said in a statement late Thursday that it had received 22 reports of cerebral venous sinus thrombosis (CVST), in which clotting forms in the sinuses that drain blood from the brain, and eight other reports of thrombosis. Four people died, according to the MHRA’s CVST results, but the agency did not immediately respond to CNN’s questions about whether there were fatalities.
The agency has recommended that the UK continue to prescribe the vaccine to all populations, claiming that such clotting cases are extremely rare and that the benefits still outweigh the risks, echoing similar assessments by the European Medicines Agency (EMA) and the World Health Organization (WHO).
However, reports of blood clots are coming in from all over the world, especially in Europe, where the AstraZeneca vaccine is widely used. Some countries have decided to ban the vaccine entirely, while others have restricted its use to specific age groups.
After the country’s medicines authority recorded blood clots among women aged 25 to 65, the Netherlands declared on Friday that it would halt administering the vaccine to people under 60 years old as a “precautionary measure.” So far, 400,000 doses of the vaccine have been distributed throughout the world.
It followed Germany, which did the same on Tuesday after 31 CVST posts. According to a Reuters report citing the country’s medicines regulator, 29 of the 31 patients were women between the ages of 20 and 63, and nine of the patients died.
At least 2.7 million Germans have received a first dose of AstraZeneca vaccine, indicating that CVST cases are still uncommon in the country. According to the country’s health ministry, complications have been identified in one out of every 100,000 AstraZeneca vaccinations. It didn’t specify what problems there were or how severe they were.
According to a study from Norway’s medicines agency, three deaths in people who suffered a combination of blood clotting, low platelet count, and hemorrhaging three to 14 days after receiving the vaccine had been confirmed as of March 30. More than 13400 people in Norway have received at least one dose of AstraZeneca.
“The Norwegian Medicines Agency believes that there is a probable link with the vaccine, but we need more research to clarify exactly what is triggering this,” it wrote.
After the vaccine, Denmark confirmed two cases of blood clots and low blood platelet counts, one of which was fatal.
Incidence is one indicator to consider. Blood clots are so common that a certain number of people are likely to get one for a variety of reasons on every given day of the week. When an individual receives a vaccine and then develops a blood clot, it isn’t always the vaccine that is to blame.
Following initial reports of clotting last month, AstraZeneca was able to point out that the overall frequency of clots in people who have taken the shot is lower than in the general population in countries where the shot is used.
In a statement to CNN on Friday, an AstraZeneca spokesperson said, “Patient safety remains the Company’s highest priority,” and pointed to authorities in the UK, EU and the WHO’s recommendations to continue its use.
“The benefit risk profile of the vaccine was reaffirmed in the EMA’s monthly safety update,” the spokesperson said.
To get a better view, scientists are focusing on the different types of clots that have been identified. CVST is uncommon to begin with, and determining whether the risk of a blood clot has increased is usually straightforward. However, it’s a little murky in this situation, partially because the population’s CVST rate isn’t obvious to begin with.
According to the MHRA, 15.8 million people in the UK have received at least one dose of the AstraZeneca vaccine. With only 30 cases of CVST or other thrombosis in the UK, the risk of forming one of these uncommon clots is 1.89 in a million.