Media reports this morning are suggesting that two National Health Service workers developed symptoms of “anaphylactoid reactions” after receiving the new Pfizer/BioNTech vaccine for COVID-19. The pair “responded adversely” following their shots, and were part of the several thousand who were vaccinated in the UK on Tuesday, the first day of the mass vaccination rollout, National Health Service England said Wednesday. Both of the patients with reactions reportedly had a history of anaphylaxis and carried an epinephrine autoinjector.
Based on these reports, health officials in the United Kingdom have advised that people with a history of significant allergic reactions should not be given the new Pfizer/BioNTech vaccine for COVID-19. “As is common with new vaccines the MHRA [Medicines and Healthcare products Regulatory Agency] 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,” said Stephen Powis, the national medical director for NHS England, in a statement. “Both are recovering well.”
The MHRA also issued new advice to health care professionals stating that any person with a significant allergic reaction to a vaccine, medicine or food — such as previous history of anaphylactoid reaction, or those who have been advised to carry an adrenaline autoinjector — should not receive the Pfizer/BioNtech vaccine. The advice also states that vaccines “should only be administered in facilities where resuscitation measures are available.”
This is a very strange situation. The contents of this vaccine (see below) do not include any protein component that could cause a true allergic reaction. Also, there were no allergic reactions reported in the 44,000 individuals in the clinical trial. I worry that there was a problem with administration of the vaccine or some other unique aspect to this site.
Despite these reports I do not think that “anyone with a history of allergic reactions should not get this vaccine.” To reassure, in the US we almost uniformly give vaccines in facilities with resuscitation equipment available. Also, until these reports are validated, I think we should withhold judgment as to what caused these reactions. There are tests that can identify allergic reactions/mast cell activation, and these should be done. The patients need to be full evaluated given the consequences of making these statements.
The Pfizer-BioNTech COVID-19 Vaccine is a white to off-white, sterile, preservative-free, frozen suspension for intramuscular injection. The vaccine contains a nucleoside-modified messenger RNA (modRNA) encoding the viral spike glycoprotein (S) of SARS-CoV-2.
The vaccine also includes the following ingredients: lipids ((4-hydroxybutyl)azanediyl) bis(hexane-6,1-diyl)bis(2-hexyldecanoate), 2-[(polyethylene glycol)-2000]-N,N-ditetradecylacetamide, 1,2-distearoyl-sn-glycero-3-phosphocholine, and cholesterol), potassium chloride, monobasic potassium phosphate, sodium chloride, dibasic sodium phosphate dihydrate, and sucrose.