BERLIN – European scientists said they had identified a mechanism that could cause the AstraZeneca PLC vaccine to cause potentially deadly blood clots in rare cases, as well as a possible treatment for them.
Two teams of medical researchers in Norway and Germany independently found that the vaccine can trigger an autoimmune disorder that causes blood to clot in the brain, which would offer an explanation for isolated incidents across Europe in recent weeks.
Several European countries briefly halted the vaccine’s launch this week, after more than 30 recipients were diagnosed with the disease known as cerebral venous sinus thrombosis or CVST. Most of the people affected were women under the age of 55.
The problem affected a small part of those who had received the vaccine, however, and after investigating, the European drug regulator determined that the benefits outweighed the potential risks of the vaccine and recommended restarting the vaccination.
Some countries, such as Germany, France and Italy, resumed vaccination with the injection of AstraZeneca on Friday, with an additional warning that it could be related to blood clotting. The French health authority, which registered three cases of CVST linked to the vaccine, advised the government on Friday to administer the vaccine only to people over 55.