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

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


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: people with white stickers with a low risk of an allergic reaction who needed to be monitored for 15 minutes, and then people given bright, can’t miss, hot pink stickers who 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. And 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, but logging him into his patient portal to get him a shot too.


The CDC reports nearly 90% of anaphylactic reactions occur within 30 minutes of the shot, and 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 including 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 a kind of testament to the skill of healthcare teams in vaccine clinics across the country on high alert, none of the 66 patients who developed anaphylaxis died. 48% were hospitalized.


More than 90% of the 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:

Click here to read about the rare reaction to the vaccine being called COVID ARM


Click here to read about who should NOT get a COVID vaccine


Click here to report an adverse reaction after a COVID vaccine

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