BBC
Scientists believe they have found "the trigger" that leads to extremely rare blood clots after the Oxford-AstraZeneca Covid vaccine. The team - in Cardiff and the US - have shown in exquisite detail how a protein in the blood is attracted to a key component of the vaccine. They think this kicks off a chain reaction, involving the immune system, that can culminate in dangerous clots. The vaccine is thought to have saved about a million lives from Covid.