New CDC Data: The Risk of a Severe Allergic Reaction after a mRNA COVID Vaccine is Extremely Low

covid vaccine reaction

In my completely anecdotal experience of monitoring hundreds of patients at COVID vaccine clinics the past few weeks, there was a common fear. The number one fear I’ve heard from people lining up is “am I going to have an allergic reaction?”

Risks of Allergic Reaction to COVID Vaccine

The answer, backed up by brand new data released from the CDC in the Journal of the American Medical Association, suggests the risk of anaphylaxis, a severe life-threatening allergic reaction, after an mRNA COVID vaccine is 0.0004%. 

In other words, very unlikely.

The CDC looked at data from more than 17 million Pfizer and Moderna mRNA vaccine doses given from December 14, 2020 to January 18, 2021.  They found 66 cases of anaphylaxis. 

Anaphylaxis after a COVID vaccine usually shows up as hives, a widespread red rash, swelling of the lips and mouth, difficulty breathing, and nausea.

Part of my job at vaccine clinics was monitoring everyone after the vaccine for an allergic reaction.  We had two groups:

  1. People with white stickers with a low risk of an allergic reaction who needed to be monitored for 15 minutes
  2. People given bright, can’t miss, hot pink stickers were flagged to wait 30 minutes because they had a history of allergies.

Fortunately, none of the people on my watch had an allergic reaction.  There was, however, a unique set of people I met- people who wanted out at the 13 or 14 minute mark. Nope, not today, not on my watch.

And then there was the 30 minute crew including a lovely 86-year-old woman who had a history of an allergic reaction to contrast dye. Her 30-minute post vaccine monitoring period was medically uneventful. We got to chatting about her driver – her just-as-wonderful 90-year-old husband – who was there, and hoping the clinic would have a spare shot for him. He didn’t have an appointment because he hadn’t been able to log into his electronic patient portal. So, we spent the 30-minute post vaccine period dodging an allergic reaction, and logging him into his patient portal to get him a shot too.

Anaphylactic Reactions to Vaccine

The CDC reports nearly 90% of anaphylactic reactions occur within 30 minutes of the shot. The vast majority happened within 15 minutes.

Nearly one-third of the 66 patients with anaphylaxis had a history of anaphylaxis to something else in the past. This included things like the flu shot, contrast dye, medications, and nuts. At least 82% of the anaphylaxis cases happened after the first COVID vaccine dose. 

And in testament to the skill of healthcare teams in vaccine clinics on high alert, none of the patients who developed anaphylaxis died. 48% were hospitalized.

More than 90% of patients with anaphylaxis were rescued with the life-saving epinephrine, usually in the form of an EpiPen. 

That quick response with an EpiPen shot as soon as anaphylaxis is spotted may very well be the key to survival.  The CDC recommends that all places that offer a COVID vaccine have EpiPens on hand and trained medical personnel to manage the reaction promptly.

So don’t let a fear of an allergic reaction keep you from getting the COVID vaccine.  If you think you have a real contraindication, talk to your doctor.

The CDC says “when considered in the context of morbidity and mortality from COVID-19, the benefits of vaccination far outweigh the risk of anaphylaxis, which is treatable.”

While we’re at it, a few useful links:

The rare reaction to the vaccine being called COVID ARM

Who should NOT get a COVID vaccine

Report an adverse reaction after a COVID vaccine