Allergy Warning Issued For Pfizer-BioNTech COVID-19 Vaccine In UK

The rollout of Pfizer Inc. PFE-BioNTech SE's BNTX COVID-19 vaccine candidate in the U.K., the first nation to authorize it on an emergency basis, brought reports of two allergic reactions Wednesday. 

What Happened: A day after the U.K. began mass COVID-19 vaccination, it emerged that it isn't advisable for people with a history of serious allergic reactions to be vaccinated with the vaccine candidate, codenamed BNT162b2.

The deduction follows the emergence of two adverse reactions on the first day of the vaccination. The affected people were staff of the U.K.'s National Health Service.

The Medical and Healthcare Products Regulatory Agency — the U.K. drug regulator — is probing whether the adverse reactions were linked to the vaccination.

The two people reportedly have a history of allergies.

"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," Stephen Powis, national medical director for the NHS, reportedly said in a statement.

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The Phase 3 clinical protocol released by Pfizer in September showed that participants with history of severe adverse reaction associated with a vaccine and/or severe allergic reaction like anaphylaxis with any component of the study were excluded from the trial.

Safety data from the Phase 3 results reported by the companies showed no serious safety concerns, with the only Grade 3 adverse events at greater than 2% in frequency being fatigue at 3.8% and headache at 2%. 

Pfizer and BioNTech reportedly suggested they were working with the investigators to better understand each case and its causes.

The U.K. drug regulator has warned anyone with serious allergic reactions to a vaccine, medicine or food against taking the shot, including those who are required to carry adrenaline shots or others who have had potentially fatal allergic reactions.

Why It's Important: BNT162b2 will be reviewed by the FDA's vaccine committee Thursday before the U.S. regulatory agency decides on Pfizer and BioNTech's emergency use authorization application.

Briefing documents released ahead of the Adcom showed that FDA staffers are convinced about the efficacy and safety of the vaccine.

A FDA vaccine committee member suggested emergency use authorization could be forthcoming as early as Friday, a day after the Adcom meeting.

PFE, BNTX Price Action: Pfizer shares were down 1.95% at $41.72 at last check Wednesday, while BioNTech shares were down 1.65% at $125.99.