A: Anaphylaxis is a severe allergic reaction that is very rare after the COVID19 vaccine.
People who have had a severe allergic reaction to a prior dose of the mRNA COVID19 vaccine should not get the second dose. If someone has had anaphylaxis to something else, they can still get the shot. Most people do just fine.
Anaphylaxis is a rare but serious allergic reaction. Symptoms of anaphylaxis include swelling of the face, throat or tongue, difficulty breathing, wheezing, hives, abdominal pain, and low blood pressure. #Anaphylaxis is an emergency and is treated with epinephrine injected into the muscle of the leg. Though it is definitely scary, anaphylaxis is treatable. Death or long-term consequences are uncommon.
Anaphylaxis is pretty darn unlikely after the COVID19 vaccine. Of people who got the #Pfizer-BioNTech vaccine, there were 11.1 cases of anaphylaxis per million doses given. Anaphylaxis is even more rare after the #Moderna vaccine, with about 2.5 cases per million doses given. This means that at most, about 1 per 100,000 folks who receive the vaccine will develop anaphylaxis. (Remember that about 1 in 59 people who get symptomatic COVID19 will die.)
People who get anaphylaxis after the first dose of an mRNA COVID19 vaccine should NOT get the second dose. People who had a non-severe allergic reaction within 4 hours of the first dose (like hives, swelling, or wheezing) should also NOT get the second dose.
If someone has a history of anaphylaxis to something else or has had an immediate allergic reaction to a different vaccine or injectable therapy, they can get the shot. They should be watched for 30 minutes after the COVID19 vaccine. Everyone else gets watched for 15 minutes. Any cases get reported to the Vaccine Adverse Events Reporting System (VAERS) as a part of our robust vaccine safety monitoring system. Because of this reporting, we know that about ¾ of all cases of anaphylaxis after the vaccine occurred within the first 15 minutes. This is a good example of how the safety monitoring system is used to help guide what we do and how to safely vaccinate.
Every place that is giving the vaccine is set up to recognize and treat anaphylaxis. They have trained healthcare professionals who know what to look for and what to do. They also have epinephrine and other medications to treat anaphylaxis and get that person safely to the hospital.
If you have a history of bad allergies or anaphylaxis, talk to your primary care clinician about getting the COVID19 vaccine.
For some light reading:
CDC MMWR Report on Anaphylaxis after PFizer-BioNTech vaccine
