People with a history of severe allergic reactions are being warned by British regulators against getting the Pfizer/BioNTech coronavirus vaccination for the time being.
The Medicines and Healthcare products Regulatory Agency said the warning should apply to people who tend to have allergic reactions to medicines, food or vaccines, according to the BBC.
The advice came after two United Kingdom National Health Service workers had allergic reactions after receiving the vaccine.
The two people have severe allergies, the BBC reported. Both carry adrenaline pens with them.
They have received treatment and Professor Stephen Powis, NHS medical director in England, said they are recovering well.
Both workers are believed to have had an anaphylactoid reaction, which can involve a skin rash, breathlessness and a drop in blood pressure.
Powis said that the warning is a precautionary measure as reactions are “common with new vaccines.”
“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,” he said.
However, severe reactions are uncommon but do occur with well-known vaccines like the flu shot.
“The fact that we know so soon about these two allergic reactions and that the regulator has acted on this to issue precautionary advice shows that this monitoring system is working well,” Professor Peter Openshaw, an expert in immunology at Imperial College London, told the BBC.
The U.K. was the first Western country to authorize a COVID-19 vaccine and began its vaccination program on Tuesday, starting with health care workers, people above the age of 80, and residents and staff in nursing homes, The Wall Street Journal reported.
The chief executive of the MHRA said that the allergic reactions had not been observed during the vaccine’s extensive clinical trials.
“We know from the very extensive clinical trials that this wasn’t a feature,” June Raine said Wednesday.
“Now that we’ve had this experience in the vulnerable populations — the groups who have been selected as a priority — we get that advice to the field immediately.”
The vaccine is administered in two doses at least 21 days apart.
In its warning, the MHRA also reminded health care workers the vaccinations should only be given in facilities where resuscitation measures are available. The agency is conducting an investigation into the allergic reactions and said it would issue further advice.
Pfizer said it and BioNTech are both cooperating with the agency in the investigation.
“In the pivotal phase 3 clinical trial, this vaccine was generally well tolerated with no serious safety concerns reported by the independent Data Monitoring Committee,” Pfizer said.
“The trial has enrolled over 44,000 participants to date, over 42,000 of whom have received a second vaccination.”
Several experts clarified that this warning and investigation should not concern the general population, but people with a history of allergic reactions should delay receiving the vaccine.
“For the general population this does not mean that they would need to be anxious about receiving the vaccination,” Stephen Evans, a professor of pharmacoepidemiology at the London School of Hygiene & Tropical Medicine, told The Wall Street Journal.
This article appeared originally on The Western Journal.