The health care workers, who both have a significant history of allergic reactions, have since recovered.
"Both of the women had their reactions started within minutes," Dr. Susan Mather, senior director of safety surveillance and risk management at Pfizer, told the US Centers for Disease Control and Prevention's Advisory Community on Immunization Practices on Friday. "So, about two minutes, and the other one just said within minutes."
The Advisory Committee on Immunization Practices convened a half-day meeting Friday to discuss the Pfizer/BioNTech Covid-19 vaccine and then, in a follow-up meeting, will vote on whether any groups should not receive the vaccine.
Following the two cases in the United Kingdom, UK health authorities gave precautionary advice that people with a significant history of allergic reactions should not be given the vaccine.