If you get a COVID-19 vaccine and you think you might be having a severe allergic reaction after leaving the vaccination provider site, seek immediate medical care by calling 911.
An immediate allergic reaction happens within 4 hours after getting vaccinated and could include symptoms such as hives, swelling, and wheezing (respiratory distress).
Delayed urticarial reactions — Occasionally, patients develop a few hives and/or mild angioedema several hours or days after administration, as with other vaccines.
Skin problems such as itchiness, rashes, hives and swelling can occur in some individuals after receiving a COVID-19 vaccine, but it's not clear how common these reactions are or how frequently they recur with a subsequent vaccination.
“Overall, severe allergic reactions to COVID-19 mRNA vaccines, including life-threatening anaphylaxis reactions such as low blood pressure and difficulty breathing, are rare, on the order of five cases per million vaccine doses administered,” noted Dr. Guerrerio.
The next time you encounter the pathogen, these responses will kick in faster and stronger, because your immune system is already primed to recognise and respond to it. This is why people who have already recovered from COVID-19 may experience more of these mild reactions.
Symptoms of anaphylaxis often occur within 15-30 minutes of vaccination, though it can sometimes take several hours for symptoms to appear.
Monitoring of the Moderna COVID-19 vaccine has found 10 cases of anaphylaxis after the administration of 4,041,396 first doses of the Moderna COVID-19 vaccine. In 9 out of these 10 cases of anaphylaxis, the recipient of the vaccine had onset of symptoms within 30 min of administration.
You probably experienced COVID-19 vaccine side effects fairly quickly when you had your initial injections. The same is true for COVID-19 vaccine booster shots: Most people notice side effects within the first 24 hours. The symptoms typically only last a day or two. Some people don't notice any side effects.
Common side effects include pain, redness and swelling at the injection site, tiredness, headache, muscle pain, chills, nausea, joint pain, and fever. Less common severe side effects include severe allergic reactions. See additional information on vaccine side effects for Pfizer-BioNTech, Moderna, and J&J.
It usually subsides within three to four days, although one report in JAMA Dermatology notes it can last up to 21 days after injection with the Moderna vaccine.
Possible side effects: Pain, redness, swelling in the arm where the shot was administered; tiredness, headache, muscle pain, chills, fever, nausea throughout the rest of the body. If any of these side effects occur, they should go away in a few days.