U.K. regulators said Wednesday that people who have a “significant history” of allergic reactions shouldn’t receive the new Pfizer-BioNTech vaccine while they investigate two adverse reactions that occurred on the first day of the country’s mass vaccination program. …“As is common with new vaccines the MHRA have advised on a precautionary basis that people with a significant history of allergic reactions do not receive this vaccination after two people with a history of significant allergic reactions responded adversely yesterday,” Powis said in a statement. “Both are recovering well.”