One of the hottest topics surrounding the COVID vaccine the past few days is allergic reactions, sparked by reports of two anaphylactic reactions after administration of Pfizer’s vaccine in the UK.
This has prompted many to ask the question: should I get the COVID vaccine if I have allergies? My goal is to clarify some of the warnings so people can make an informed decision. The main takeaways focus on differentiating between allergic vs. anaphylactic reactions:
- If you have food allergies or allergies to one medicine, you do not need to avoid the Pfizer vaccine
- If you have had anaphylactic-level reactions and normally carry an auto-injectable device with epinephrine (e.g. EpiPen), you can either wait for more data or get vaccinated in a more controlled setting like a hospital or outpatient clinic.
- There is no virus in the vaccine, so you can not contract COVID from the vaccine
So what happened in the UK? Last week, Britain’s Medicines and Healthcare Products Regulatory Agency (MHRA) was the first in the world to approve the vaccine developed by Germany’s BioNTech and Pfizer. Just this past Tuesday, Britain rolled out the Pfizer vaccine starting with the elderly and frontline workers. Two National Health Service workers developed anaphylactic reactions that were described as non life-threatening. Both recipients had a history of severe allergies and carried epinephrine pens routinely. Fortunately, both patients are recovering.
Initially, the MHRA put out a precautionary guidance stating people with a history of significant allergic reaction should not take the vaccine, which was quickly clarified to anybody with anaphylaxis to a vaccine, medicine or food. Many in the science community are concerned that this advice is too broad, particularly since there is no trace of nuts, eggs, or any food in the vaccine.
What is actually in this vaccine, and what could explain the allergic reaction? The Pfizer vaccine is based on new technology, designed to get the body to build up defenses against COVID on its own. The key ingredient in the Pfizer vaccine is messenger RNA (mRNA), which teaches the body how to fight against the proteins that help COVID-19 invade our cells. The mRNA is packaged up with salt, fats and sugar in a whitish, preservative-free solution to help make it deliverable into our muscle.
Here is a list of the components:
- A nucleoside-modified messenger RNA (modRNA) encoding the viral spike glycoprotein of SARS-CoV-2 (this is what makes the shot work, and is NOT the virus)
- Lipids (i.e. fatty substances) including:
- 2-[(polyethylene glycol)-2000]-N, N-ditetradecylacetamide,
- Potassium chloride
- Monobasic potassium phosphate
- Sodium chloride
- Dibasic sodium phosphate dihydrate
While none of these ingredients are known to be highly allergenic, one possibility is a component found in one of the ingredients called polyethylene glycol (PEG). PEG helps stabilize the vaccine and is not in other types of vaccines.
Patients with severe allergic reaction history were excluded from the clinical trials, which is common, and helps explain why we are seeing these events show up in real-time. The good news for those predisposed to allergic reactions is that other vaccine options will become available that may avoid the allergic trigger found in the Pfizer vaccine.
Transparency during vaccine rollout is paramount to gain public trust. Events such as these two allergic reactions will help better equip patients and healthcare workers as we prepare for the FDA’s Emergency Use Authorization (EAU) of the vaccine in the U.S. The COVID vaccine has a particularly big magnifying glass on it, and I think we have to resist the urge to panic or “headline react.”
There is enough mistrust in the vaccine that adding a headline to avoid the vaccine if you have a history of allergies may dissuade millions of people from getting vaccinated. Allergic reactions, and certainly anaphylactic reactions, are not something to take lightly. Fortunately, these reactions are rare and treatable in the right setting, and the benefit of protecting against COVID-19 likely outweighs the risk.
Dr. George C. Hwang, known to his patients as Dr. Chaucer, is a practicing anesthesiologist who also helps to run Mind Peace Clinics in Arlington. He has written for multiple journals, textbooks and medical news outlets, and has been living in Arlington for the past 15 years.