The UK's medicines regulator has said that at least 30 people in the United Kingdom have experienced rare types of blood clots after receiving the Oxford-AstraZeneca vaccine, but warned it was too early to know whether the shot itself triggered the clots. The Medicines and Healthcare products Regulatory Agency (MHRA) said in a statement late Thursday it received 22 reports of cerebral venous sinus thrombosis (CVST), where clotting forms in the sinuses that drain blood from the brain, and eight other reports of thrombosis, out of a total of 15.8 million people who had been given at least one dose of the vaccine by March 21. A breakdown of the MHRA's CVST data showed four people had died, but the agency did not immediately respond to CNN's questions to confirm whether there had been fatalities.