The US Food and Drug Administration said on Thursday it was working with Pfizer to revise a fact sheet for recipients of the Pfizer-BioNTech Covid-19 vaccine after two people had allergic reactions.

The two people, both health workers, were vaccinated in Alaska and one of them had a serious or “anaphylactic” reaction resulting in hospitalisation.

Doran Fink, deputy director of the FDA’s division of vaccines said, “All of these individuals were treated with appropriate medical intervention and thankfully, all are recovered or recovering.

“We anticipate that there may be additional reports, which we will rapidly investigate.”

He added that US authorities, including the Centers for Disease Control and Prevention, were investigating the two cases and working with Britain to better understand two similar cases that occurred there.

“While the totality of data at this time continues to support vaccinations under the Pfizer EUA (emergency use authorization), without new restrictions, these…