Britain's medicine regulator said anyone with a history of anaphylaxis to a medicine or food should not get the Pfizer-BioNTech COVID-19 vaccine, giving fuller guidance on an earlier allergy warning about the shot.
Starting with the elderly and front-line workers, Britain began mass vaccinating its population on Tuesday, part of a global drive that poses one of the biggest logistical challenges in peacetime history.
The Medicines and Healthcare Products Regulatory Agency (MHRA) said there had been two reports of anaphylaxis and one report of a possible allergic reaction since rollout began.