Results from 64,900 vaccines: Allergy Risk?
Journal of the American Medical Association Research Study: March 2021
(reference and link to the study are at the bottom of the page)
Easy-to-Read Results Summary:
- Researchers did this study based on the fact that many are nervous to get the vaccines due to having allergies themselves and all the media-hype regarding allergic reactions causes some people to avoid the vaccines.
So... what is the truth?
- Study was done at Massachusetts General Brigham (the Original Harvard hospital!)
- Studied what happened the 3 days after the first vaccine (the time of highest chances for allergy symptoms)
- 40% got Pfizer, 60% Moderna
Mild allergic reactions
- 1 out of every 50 vaccines caused mild allergic reactions (itch, hives, swelling)
- Moderna (2.2% of the shots caused mild allergy) vs Pfizer (2% of the shots): not much difference
- 98% of all people had no allergic reactions at all (that is a nice, safe number)
Significant allergic reactions (anaphylaxis)
- Occurred in 1 out of every 3700 Pfizer shots (i.e. .027% of the shots)
- Occurred in 1 out of every 4300 Moderna shots (i.e. .023% of the shots)
- In total, there were 5 anaphylactic reactions per 20,000 vaccines (that is a really safe number compared to many other drugs)
Timing for significant allergic reaction (anaphylaxis)
- An average of 17 minutes after the shot
- The range was from immediately after the shot up to 2 hours later at the latest
- 7 of the 16 patients had mild skin reactions
- 9 of the 16 patients had "measurable" but not life-threatening reactions
- 3 did not seek any medical attention
- 1 went to the ICU and recovered
- 9 out of 16 patients needed an epinephrine shot (EpiPen) and all recovered
- There were no severe anaphylactic reactions (having shock or requiring intubation)
Who was most likely to get anaphylaxis?
- Out of 16 patients in total, 5 (31%) had a history of anaphylaxis
- 10 out of 16 (61%) had a history of allergies (probably not significantly different than the usual population)
"I have a history of anaphylaxis, what is my risk?"
- Assuming there were 4000 individuals with severe food or drug allergies in this group (this is the expected #)
- Only 5 out of 4000 people with a history of anaphylaxis get an anaphylactic reaction (1 out of every 800)
- Knowing that this is a group of people who are used to planning for anaphylaxis and should have an EpiPen, and who know they have to use it when exposed to a known allergen (like me when I accidentally eat shrimp), that is an incredibly low number.
- I took my EpiPen with me when I got mine. No problems! Only 1 out of every 800 times would someone need to use it
- Since the results were reported by the employees themselves, and not confirmed by doctors, we cannot ensure that these were truly anaphylactic reactions (people do tend to overestimate such responses = my opinion)
- The researchers, Harvard-famous allergy experts, stated, "... the overall risk of anaphylaxis to an mRNA COVID-19 vaccine remains extremely low"
If you have had an anaphylactic reaction in the past (like I have), I recommend:
- Just take your EpiPen and wait a while after your shot if you have had anaphylaxis before. However, don't sweat it.
You have a higher chance of getting into a car accident on the way to the shot than you do of getting an anaphylactic reaction
Did you get your vaccine? How did you do?
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Reference: Blumenthal KG, Robinson LB, Camargo CA, et al. Acute Allergic Reactions to mRNA COVID-19 Vaccines. JAMA. Published online March 08, 2021. doi:10.1001/jama.2021.3976
Note that Dr. Thomas' posts are for informational purposes only, and are not meant to be specific medical advice for individuals. Always seek the advice of your healthcare provider with any questions regarding your own medical situation.
DONALD THOMAS, MD