LONDON (AP) — Britain’s medical regulator says people with a history of serious allergic reactions shouldn’t receive the COVID-19 vaccine from Pfizer and BioNTech as investigators look into whether two reactions on the first day of the country’s vaccination program were linked to the shot. The medical director for the National Health Service in England said the advice was issued on a “precautionary basis” and that the people who had reactions had recovered. The medical regulator has said people should not get the vaccine if they have had a significant allergic reaction to a vaccine, medicine or food. Pfizer and BioNTech say they are working with authorities but that late-stage trials found no serious safety concerns.