Seven people have died from the unusual blood clots after getting the Oxford-AstraZeneca vaccine in the United Kingdom, the nation’s medical regulator said.
In total, 30 people out of 18 million vaccinated by 24 March had these clots. It is still not clear if they are just a coincidence or a genuine side effect of the Oxford vaccine.
The Medicines and Healthcare Products Regulatory Agency says the benefits continue to outweigh any risk.
The World Health Organization and the European Medicines Agency have echoed this conclusion.
A spokeswoman for AstraZeneca said: “Patient safety remains the company’s highest priority.”
However, concern has led to other countries including Germany, France, the Netherlands and Canada to restrict the vaccine’s use only to older people.
The data released by the MHRA showed 22 cases of cerebral venous sinus thrombosis (CVST) which is a type of blood clot in the brain.
These were accompanied by low levels of platelets, which help form blood clots, in the body. The MHRA also found other clotting problems alongside low platelet levels in eight people.
Investigations are under way to determine if the AstraZeneca vaccine is causing the very rare blood clots. Earlier this week the European Medicines Agency said it was “not proven, but is possible”.
There were no reports of blood clots from the Pfizer/BioNTech vaccine it said, adding that “our thorough review into these reports is ongoing.”
AstraZeneca said last month following US efficiency trials that its vaccine is 79 percent effective at preventing the disease and does not increase the risk of blood clots.
Germany has reported 31 CVSTs and nine deaths out of the 2.7 million people vaccinated there, with most cases in young or middle-aged women.