U.K. regulators say that those people with history of allergic reactions to medicine or food should avoid the COVID-19 vaccine, according to a Wednesday report from the BBC.
The United Kingdom began the process of rolling out the vaccine on Tuesday, following a Dec. 2 approval.
The urgent guidance comes after at least two NHS workers experienced allergic reactions to the new Pfizer-BioNTech vaccine on Tuesday. Both workers — who reportedly have a history of experiencing allergic reactions — are expected to recover.
What are the details?
Regulators at the Medicines and Healthcare products Regulatory Agency said that the two workers experienced an "anaphylactoid reaction," which is "much milder than anaphylaxis."
The reaction, according to to the news agency, "tends to involve a skin rash, breathlessness, and sometimes a drop in blood pressure."
NHS medical director Stephen Powis said that the two unnamed NHS workers are on the mend.
"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 have responded adversely," he said in a statement on the matter.
According to ABC News, regulators will work to investigate the NHS workers' reactions to the vaccine.
Dr. June Raine, head of the United Kingdom's medical regulatory agency, explained, "We're looking at two case reports of allergic reactions,'' adding, “We know from the very extensive clinical trials that this wasn't a feature."
"But if we need to strengthen our advice, now that we have had this experience with the vulnerable populations, the groups who have been selected as a priority, we get that advice to the field immediately," she said.
Business Insider reported that health officials have yet to reveal which element of the vaccine caused the reaction in the two NHS workers.
"All regions involved with the vaccination program have been alerted," NHS England said according to the outlet, "and from Wednesday all patients receiving the vaccine will be asked beforehand if they have a history of allergic reactions."
Further, regulators say that the vaccine should only be administered in facilities where "resuscitation measures are available."