Is the COVID Vaccine Safe for People With Allergies?
An immunologist weighs in on whether the vax can cause unwanted (or even dangerous) complications.
We're a year into the pandemic, and the calvary is no longer just coming—it has arrived. Pfizer and Moderna's two-dose messenger-RNA vaccines, first approved by the Food and Drug Administration (FDA) in December 2020, are both around 95% effective at preventing moderate to severe infection. And tens of millions of Americans have safely received them.
A third vaccine, developed by Johnson & Johnson, earned FDA approval on February 27, and is 66% effective overall. However, its rollout hasn't gone quite so smoothly: On April 13, 2021, the Centers for Disease Control and Prevention (CDC) and the FDA announced in a joint statment that this vaccine was being put on "pause" after six American women ages 18 to 48 developed a type of dangerous blood clot, combined with low levels of blood platelets, within six to 13 days of receiving the shot. After reviewing the evidence, federal health experts determined on April 23 that the J & J vaccine is safe and that its use should resume, effective immediately, with a brief caveat that women younger than 50 should be aware of the rare risks of blood clots.
So far, almost 30% of Americans have received their full dose of the vaccine (two doses of Pfizer or Moderna or one dose of J & J). By and large, side effects have been mild to moderate and not cause for serious concern. However, a small number of people have reported anaphylaxis, a severe allergic adverse reaction to the shot, leading some people with allergies to wonder if the vaccine is safe for them.
From the most recently released data (January 6) from the Centers for Disease Control and Prevention (CDC), there were 21 confirmed cases of anaphylaxis after receipt of the Pfizer vaccine—17 of which occurred in people with a documented history of severe allergic reactions (though we don’t yet know what specifically they were allergic to). All of those patients recovered. On January 22, the CDC released data on allergic reactions to the Moderna shot, noting 10 confirmed cases of anaphylaxis, nine of which occurred in people with a documented allergic history. Johnson & Johnson says that no cases of anaphylaxis occurred during its clinical trials, but we don't have CDC-backed data to confirm this yet.
AstraZeneca's vaccine candidate (already approved in some countries but not in the U.S.) appears to be 76% effective after the first shot and 82% effective after the second. However, distribution of this vaccine was briefly suspended in several European countries after reports surfaced of 37 cases of dangerous blood clots in the more than 17 million people who had received the shot in the European Union and UK. Officials from the European Medicines Agency say there’s “no indication” right now that the clots were associated with the shot, and they have since resumed the rollout of this vaccine across Europe. But TBD on what this means for approval here in the U.S. or what it might indicate about allergic reactions.
Novavax, another company working on vaccine development, says its two-shot vaccine candidate is 89% effective in the UK. We don't yet know information on allergic reactions for this vaccine yet.
For now, where does that leave you? Should people with a history of allergic reactions still get the shot? The CDC says yes, unless you are allergic to one specific ingredient in the Pfizer and Moderna vaccines: polyethylene glycol. It’s a compound found in the mRNA vaccines and some other medications that causes a rare allergic reaction in a very small number of people. The CDC also recommends that people who had a severe allergic reaction to the first dose of the COVID vaccine (no matter which of the three options you got) should not get a second dose. The agency is asking patients who have allergic reactions to the COVID vaccine to contact their healthcare provider, who can enter their information into the U.S. government's Vaccine Adverse Event Reporting System (VAERS) for data collection.
We asked allergist and immunologist Purvi Parikh, M.D., a spokesperson for the Allergy & Asthma Network and co-investigator for the COVID-19 vaccine trials, to share her thoughts on COVID vaccine safety for folks worried about allergic reactions. Here’s what she has to say. (Hint: Her answers will probably help calm your fears.)
HealthCentral: What is in the COVID vaccines? Are there any ingredients people should be concerned about?
Purvi Parikh, M.D.: Among the two mRNA vaccines, one ingredient is polyethylene glycol. We don’t know for sure if this is the main culprit causing a reaction, but this is what we think it may be. The other ingredients are basically sugars, fats, and salts, which are things that people eat on an everyday basis and have in their bodies naturally. (Editor's note: The Johnson & Johnson vaccine does not contain polyethylene glycol.)
That being said, an allergy to polyethylene glycol is pretty rare. Having an actual vaccine allergy is also very rare. We did a big study on this in one of our national allergy and immunology journals, and we found that it’s more likely that you’ll be struck by lightning than have a life-threating anaphylactic reaction to a vaccine. The worry is pretty low—the odds are 1.3 out of a million that you’ll have a true life-threatening allergic reaction. Just to give people peace of mind.
HC: What about people with other types of severe allergies to food or environmental factors—should they get the COVID shot?
PP: If you are allergic to an ingredient in the vaccine such as the polyethylene glycol, then we say you should avoid it. But if you aren’t allergic to any of those ingredients and you have other allergies—let’s say food, medication, or environmental factors—there’s no need to avoid the vaccine. We recommend that you get it because COVID-19 is far more dangerous. A main recommendation for people with allergies is that they get it at a medical facility that is equipped to treat anaphylaxis and allergic reactions, and that they wait for 30 minutes after getting the vaccine before going home, which is a little longer than the 15 minutes we ask the general public to wait.
HC: Does one vaccine appear to have caused more allergic reactions than another?
PP: Reactions to Pfizer seemed more prominent initially because that was what everyone was getting first. Then Moderna rolled out, and now we are hearing some cases from Moderna as well. I can’t really say if one is more common than the other. But both have pretty much the exact same ingredients, so just from a logical standpoint, the number of reactions should be fairly equivalent between the two. (Editor's note: No data have yet been reported on allergic reactions to the Johnson & Johnson vaccine.)
HC: If someone is worried about whether their existing allergies might trigger a reaction to the COVID vaccine, who should they talk to about this?
PP: I recommend they talk with their allergist, first and foremost. They are the experts in the field. Again, we are encouraging those with allergies to get the vaccine unless they are allergic to a specific ingredient in one of these two vaccines. Thousands of people with allergies have already received the vaccine with no issue, even in the clinical trials.
Because these allergic reactions are so rare, people should not be afraid to get the vaccine. In fact, they should be more afraid of getting COVID-19 than any potential allergic reaction. The virus is far more common and deadly at this point.
CDC Report on Pfizer Allergic Reactions: Centers for Disease Control & Prevention. (2021). “Allergic Reactions Including Anaphylaxis After Receipt of the First Dose of Pfizer-BioNTech COVID-19 Vaccine — United States, December 14–23, 2020.” cdc.gov/mmwr/volumes/70/wr/mm7002e1.htm
CDC Report on Moderna Allergic Reactions: Centers for Disease Control & Prevention. (2021). “Allergic Reactions Including Anaphylaxis After Receipt of the First Dose of Moderna COVID-19 Vaccine — United States, December 21, 2020–January 10, 2021.” cdc.gov/mmwr/volumes/70/wr/mm7004e1.htm?s_cid=mm7004e1_w
CDC Guidance on Allergic Reactions: Centers for Disease Control & Prevention. (2020). “COVID-19 Vaccines and Allergic Reactions.” cdc.gov/coronavirus/2019-ncov/vaccines/safety/allergic-reaction.html
Johnson & Johnson Phase 3 Data: Johnson & Johnson. (2021). “Single-Shot Janssen COVID-19 Vaccine Candidate Met Primary Endpoints in Interim Analysis of its Phase 3 ENSEMBLE Trial.” jnj.com/johnson-johnson-announces-single-shot-janssen-covid-19-vaccine-candidate-met-primary-endpoints-in-interim-analysis-of-its-phase-3-ensemble-trial
Novavax UK Trial Data: Novavax. (2021). “Novavax COVID-19 Vaccine Demonstrates 89.3% Efficacy in UK Phase 3 Trial.” ir.novavax.com/news-releases/news-release-details/novavax-covid-19-vaccine-demonstrates-893-efficacy-uk-phase-3
AstraZeneca Efficacy Results: University of Oxford. (2021.) “Oxford coronavirus vaccine shows sustained protection of 76% during the 3-month interval until the second dose.” [ox.ac.uk/news/2021-02-02-oxford-coronavirus-vaccine-shows-sustained-protection-76-during-3-month-interval (https://www.ox.ac.uk/news/2021-02-02-oxford-coronavirus-vaccine-shows-sustained-protection-76-during-3-month-interval)
Johnson & Johnson FDA EUD: Food and Drug Administration. (2021.) “FDA Issues Emergency Use Authorization for Third COVID-19 Vaccine.” fda.gov/news-events/press-announcements/fda-issues-emergency-use-authorization-third-covid-19-vaccine