After two health-care workers reacted adversely to injections of the new Pfizer-BioNTech vaccine, British regulators on Wednesday ordered hospitals not to inject people who have a history of “significant” allergic reactions.
The new warnings come just a day after Britain launched the first mass immunization campaign in the West, with the aim of vaccinating the whole country against the coronavirus.
Two staffers with Britain’s National Health Service suffered symptoms of “anaphylactoid reaction” when they received vaccinations at a hospital on Tuesday.
NHS officials said both workers have a history of serious allergies and carry adrenaline pens to quickly quell symptoms, which can include skin reactions, low blood pressure, constricted airways and dizziness or fainting.
“Both are recovering well,” said NHS medical director Stephen Powis.
As is common with new vaccines, Britain’s regulator, the Medicines and Healthcare Products Regulatory Agency (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.
The two-shot Pfizer vaccine appears to be on the cusp of regulatory clearance in the United States by the Food and Drug Administration, after a 53-page review published Tuesday confirmed that the vaccine meets the standard for emergency-use authorization. The federal government has ordered 100 million doses, which can start being delivered as soon as regulators give the go-ahead.
A spokeswoman for Pfizer said the pharmaceutical giant, which developed the new vaccine with the German firm BioNTech, was advised by British regulators of two “yellow card reports,” associated with allergic reactions due to vaccine. Yellow cards are issued in Britain when drugs or vaccines create side effects, which must be reported.
“As a precautionary measure, the MHRA has issued temporary guidance to the NHS while it conducts an investigation in order to fully understand each case and its causes. Pfizer and BioNTech are supporting the MHRA in the investigation,” the drug company said.
“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,” it said. “The trial has enrolled over 44,000 participants to date, over 42,000 of whom have received a second vaccination.”
On the first day of its rollout, “several thousand” people received injections at 50 hospitals around England. Britain hopes to inoculate as many as 2 million people by the end of the year.
In remarks to journalists via Britain’s Science Media Center, Stephen Evans, a professor of pharmacoepidemiology at the London School of Hygiene & Tropical Medicine, said: “Allergic reaction occurs with quite a number of vaccines, and perhaps even more frequently with drugs. So it is not unexpected.”
Evans said the Pfizer data showed that about 0.6 per cent of people had some form of an allergic reaction to the vaccine in the clinical trials (although 0.5 per cent also had a reaction to the placebo).
So there was a genuine excess of an allergic reaction, but this was small and the true rate is not known, he said, adding that there is a lot of uncertainty around that estimate.
“What would be wise,” as regulators advised on Wednesday, “would be for anyone who has known severe allergic reaction, such that they need to carry an EpiPen, to delay having a vaccination until the reason for the allergic reaction has been clarified,” Evans said.