Britain left the European bloc’s single market on Thursday night, in the biggest single economic change the country has experienced since World War II.
The advisory comes after two National Health Services employees, both with a history of severe allergies, had bad reactions after receiving the new Pfizer and BioNTech vaccine Tuesday, the first day of the U.K.'s nationwide immunization campaign.
British health officials said Tuesday marked a turning point in the country's battle with the virus, an illness that has infected more than 67 million people around the world and has killed more than 1.5 million people, Johns Hopkins University data shows.