If you have an allergic reaction to your first dose of an mRNA COVID-19 vaccine, you should not get the second shot, the Centers for Disease Control and Prevention advises. That guidance applies to both severe and non-severe allergic reactions, the CDC says on its website. The mRNA vaccines are the two-shot regimens produced by Moderna and Pfizer; they're called mRNA vaccines because they use messenger RNA to prompt the immune system to create antibodies to the coronavirus. The newly approved one-shot Johnson&Johnson vaccine is not an mRNA vaccine—it uses a weakened, harmless adenovirus to provoke an immune response. Read on to see if you should get the vaccine—and to ensure your health and the health of others, don't miss these Sure Signs You've Already Had Coronavirus.
CDC Has "Learned of Reports" of "Severe Allergic Reactions" But They Are Rare
"CDC has learned of reports that some people have experienced severe allergic reactions—also known as anaphylaxis—after getting a COVID-19 vaccine," the agency says. "An allergic reaction is considered severe when a person needs to be treated with epinephrine or EpiPen or if they must go to the hospital."
People who have an "immediate allergic reaction" to an mRNA vaccine that is non-severe—meaning, not requiring emergency care—also should avoid the second dose. "CDC has also learned of reports that some people have experienced non-severe allergic reactions within 4 hours after getting vaccinated (known as immediate allergic reactions), such as hives, swelling, and wheezing (respiratory distress)," the agency says.
You May Get "COVID Arm," Which is OK
An allergic reaction is different from "COVID arm," an red, itchy, swollen, or painful rash at the site of the shot, which may begin a few days to a week after the initial vaccination.
If you get "COVID arm" after an mRNA vaccine, you should still get the second shot, the CDC says. The agency advises telling the person giving you the shot that you had "COVID arm;" they may advise you to take the second shot in the other arm.
"CDC does not currently know whether people who experience 'COVID arm' after the first dose will have a similar reaction after the second dose," the agency says. "However, currently available evidence suggests that having this type of reaction after the first dose does not increase your risk of having a severe allergic reaction after the second dose."
Allergic reactions to the vaccine are extremely rare. In the United States through Jan. 24, there were 50 reported cases of anaphylaxis among 9,943,247 doses of the Pfizer vaccine. That works out to 5 cases of anaphylaxis per million doses administered. For the Moderna vaccine, there were 21 reported cases of anaphylaxis out of 7,581,429 doses—2.8 cases of anaphylaxis per million doses given.
How to Stay Healthy During This Pandemic
As for yourself, do everything you can to prevent getting—and spreading—COVID-19 in the first place: Wear a face mask, get tested if you think you have coronavirus, avoid crowds (and bars, and house parties), practice social distancing, only run essential errands, wash your hands regularly, disinfect frequently touched surfaces, and to get through this pandemic at your healthiest, don't miss these 35 Places You're Most Likely to Catch COVID.