Aaron Rodgers said allergy kept him from getting COVID vaccine. How common is it?
Allergic reactions to COVID-19 vaccines are possible, but they are extremely rare, especially the more severe ones. Importantly, they can happen after any vaccine.
Anaphylaxis — a severe, potentially life-threatening allergic reaction — has occurred in about two to five people per million vaccinated individuals in the U.S., according to the Centers for Disease Control and Prevention.
Health experts advise people with a known allergy to one of the ingredients in either of the three COVID-19 vaccines to speak with their doctor about which coronavirus shot is safest for them.
The issue has gained some attention after Green Bay Packers quarterback Aaron Rodgers said he did his own research before learning he’s allergic to an ingredient in the mRNA COVID-19 vaccines, including the Pfizer and Moderna shots, which share a similar makeup, McClatchy News reported.
“In actuality, it was pretty easy to eliminate two of them and it didn’t involve going into the questionable history of some of their criminal activities or fraud cases,” Rodgers said of the vaccines on Nov. 5 on the Pat McAfee Show Live. “I have an allergy to an ingredient that’s in the mRNA vaccines.”
The NFL superstar said the Johnson & Johnson coronavirus vaccine was also not an option for him, citing “adverse events” that have been reported in some people, including blood clots.
Rodgers did not reveal what ingredient he’s allergic to in the Pfizer or Moderna vaccines, but studies point to polyethylene glycol (PEG), an inactive portion of the mRNA shots called an “excipient.”
“Excipients are necessary and added to a vaccine for specific purposes such as stimulating a stronger immune response, preventing contamination by bacteria or stabilizing the potency of the vaccine during transportation and storage,” a team of allergists said in April.
Some other inactive ingredients include a variety of lipids that help with stability, salts — such as potassium chloride and sodium acetate — and sugars (sucrose). The only active ingredient in the Pfizer and Moderna vaccines is mRNA, a subtype of RNA that makes up the coronavirus’s genetic material and can already be found in our bodies. It carries directions that teach our cells to produce antibodies against the coronavirus.
That’s why the team of allergists says people with a history of food or medication allergies can safely receive a coronavirus vaccine, especially since both options do not contain any foods such as eggs, drugs, preservatives or latex — all common allergens.
Several skin prick tests have linked PEG to allergic reactions following vaccination with the Pfizer and Moderna vaccines.
“It’s believed that COVID-19 vaccine-related allergic reactions are caused by PEG,” Dr. David Lang, an allergist and chair of Cleveland Clinic’s Department of Allergy and Clinical Immunology, said in October. “Whether some of the reactions are occurring via another mechanism is unclear at this time.”
“Even though there is a risk of anaphylaxis, it’s still very small — and the potential benefit from the COVID-19 vaccination clearly exceeds the potential for harm,” Lang added. “The situation is evolving, however, and we’ll learn more as we continue to work with these vaccines.”
PEG is closely related to polysorbate, an ingredient in the J&J vaccine, the CDC says; if you’re allergic to PEG, you should not get an mRNA vaccine and instead get the J&J shot. The same thinking applies to polysorbate allergies.
Most allergic reactions occur in people with a history of allergies
A CDC study published in January found 21 cases of anaphylaxis among more than 1.8 million recipients of a first dose of the Pfizer vaccine, or about 11 cases per million vaccine doses administered; 81% of affected people had a history of allergies or allergic reactions to drugs, medical products, foods, insect stings or other vaccines. Some have had anaphylaxis events in the past.
A separate study published in March also found allergic reactions after COVID-19 vaccination were rare.
Of 64,900 health care employees, 98% did not experience an allergic reaction. The majority of the remaining 2% who did had allergy histories, with 31% having prior anaphylaxis.
The study also found people with severe food and drug allergy histories had a safe vaccination experience.
“The overall risk of anaphylaxis to an mRNA COVID-19 vaccine remains extremely low and largely comparable to other common health care exposures,” the researchers wrote in their study published in the journal JAMA.
The CDC also warns against taking allergy medications before COVID-19 vaccination to prevent allergic reactions because it’s unclear how those drugs could affect the body’s immune response.
Experts define an allergic reaction as one that requires hospitalization or treatment with epinephrine. Immediate reactions occur within four hours of vaccination and can cause hives, swelling and breathing problems.
This story was originally published November 5, 2021 at 6:12 PM with the headline "Aaron Rodgers said allergy kept him from getting COVID vaccine. How common is it?."
