SAN DIEGO (KGTV) — As Pfizer’s COVID-19 vaccine rolls out to healthcare workers, at least four have had severe allergic reactions after getting the shot.
The cases include two healthcare workers in Alaska and two in the UK. In the UK cases, both individuals carried epipens.
“So these were people with a history of severe allergies and not just severe allergies like you got hives, but they had allergies where they encounter certain things in the environment and their body shuts down,” said UC San Francisco infectious disease expert Dr. Peter Chin-Hong.
All four have apparently recovered.
At this point, doctors aren’t sure what caused the reactions. Generally speaking, allergies when your immune system overreacts to something harmless.
Pfizer’s vaccine has 10 ingredients that fit into four categories.
The active ingredient is mRNA. These are temporary genetic instructions for your cells to build a small, harmless fragment of the virus’ shell to train your immune system, similar to setting up a punching bag to train a boxer.
Then there are fats to stabilize and transport the mRNA, salts to maintain the pH, and sugar to prevent the solution from degrading while freezing.
All the ingredients are considered standard. Dr. Chin-Hong says he was struck by what’s not in the vaccine.
“They didn't have egg products or any of those kinds of things that people might be allergic to,” he said. “They didn't have live virus, which might also elicit a response.”
The only ingredient with a history of allergic reactions is polyethylene glycol, or PEG, one of the fats that acts as an oily bubble for the mRNA.
PEG is also in Moderna’s vaccine and it’s common; it’s found in ultrasound gel, laxatives, injectable steroids and other products.
Although PEG allergies are rare, the FDA says people who are allergic to any of the 10 ingredients should not get the vaccine.
However, experts say people with common allergies should not worry.
“A lot of people have minor food allergies or bee-sting allergies or peanut allergies or environmental allergies,” said Dr. Christian Ramers of Family Health Centers of San Diego. “They may even carry an epi-pen because sometimes it gets severe. Those people would not be excluded from getting this vaccine.”
The American College of Allergy, Asthma and Immunology issued guidance saying people with those common allergies, including to latex and medications, “are no more likely than the general public to have an allergic reaction” to the vaccine.
After every shot, people who get vaccinated have to wait 15 minutes so healthcare workers can monitor them for a reaction. Should one occur, interventions like epi-pens are very effective.
The FDA said people with a history of allergic reactions to vaccines or injectable drugs can still get the shot, but they should wait 30 minutes for slightly longer monitoring.
The odds of having a severe allergic reaction to any vaccine is about 1 in 760,000. That means you’re more likely to be struck by lightning in a given year, which the CDC estimates is about 1 in 500,000.