COVID Vaccine & Allergic Reaction FAQS

What are the different COVID vaccines that are available?

There are two vaccines that have been approved by the FDA for EUA (emergency use authorization). One is manufactured by Pfizer-BioNTech and the other by Moderna.

Is the COVID vaccine safe?

The COVID vaccines were held to the same rigorous safety and effectiveness standards as all other types of vaccines in the United States. Both the Moderna and Pfizer-BioNTech vaccines are mRNA vaccines. They do not change your DNA.

What is an mRNA vaccine?

RNA vaccines are faster and cheaper to produce than traditional vaccines, and an RNA-based vaccine is also safer for the patient, as they are not produced using a live vaccine. The benefit of mRNA vaccines, like all vaccines, is that those vaccinated gain this protection without ever having to risk the serious consequences of getting sick with COVID-19. The COVID vaccines are the first mRNA vaccines approved by the FDA for EUA in the US. However, researchers have been studying and working with them for decades.

How many shots of the COVID vaccine will I need?

The data we have so far for both the Pfizer-BioNTech and Moderna COVID vaccines suggest that you need two doses of the vaccine to be effective.

What side effects should I expect from the vaccine?

Based on what we know so far, most people will have mild, short-term side effects after getting a COVID-19 vaccine. Symptoms may include fever, fatigue, headache, muscle pain, or joint pain. Some patients may have swelling and redness at the site of the injection that can last for a few days. These are not allergic symptoms but part of the immune response to the vaccine. They will not prevent you from getting the second dose of the vaccine.

What is vaccine allergy? 

Similar to medications or foods, people can be allergic to a vaccine. Most reactions are mild, such as hives as the only symptom, while others are more severe. A severe allergic reaction is called anaphylaxis. Symptoms of a severe allergic reaction often start very quickly (usually within minutes)—and almost always within 4 hours of vaccination—and typically include multiple parts of the body: hives on the skin; swelling of mouth, lips, tongue or throat; shortness of breath, wheezing, or chest tightness; or low blood pressure or loss of consciousness.

What about redness and swelling at the injection site? Is that an allergic reaction?

Sometimes vaccines can cause large local reactions at the injection site, and these can begin hours or days after the vaccination. The skin at the site of vaccination can become sore, swollen, red, and painful. Sometimes, it can also become itchy. The symptoms can last several days. With the COVID-19 vaccine, this reaction can be delayed 7-10 days without any symptoms prior to this. Although this type of reaction can be uncomfortable, it is not an allergic reaction to the vaccine. This does not increase your risk of an allergic reaction with the next dose of the COVID-19 vaccine.

Do I have to avoid the Pfizer-BioNTech or Moderna COVID-19 vaccine if I have a food or drug allergy?

You can still receive either COVID-19 vaccine if you have a food or drug allergy. US-based experts have advised avoidance of the vaccine only for patients with a history of a severe reaction after a previous dose of this COVID-19 vaccine or any ingredient in this vaccine, including polyethylene gycol (PEG) or polysorbate, due to the possible cross-reactivity.

The FDA states:
“Do not administer Pfizer-BioNTech COVID-19 Vaccine to individuals with known history of a severe allergic reaction (e.g., anaphylaxis) to any component of the Pfizer-BioNTech COVID-19 Vaccine.”
and
“Do not administer the Moderna COVID-19 Vaccine to individuals with a known history of a severe allergic reaction (e.g., anaphylaxis) to any component of the Moderna COVID-19 Vaccine.”

The CDC has recommended that any patient with a history of severe allergic reaction to an injectable medication (intravenous, intramuscular, or subcutaneous) or an immediate (<4 hours) or severe allergic reaction to a prior COVID-19 vaccine be evaluated by an allergy specialist to determine whether they can safely receive the COVID-19 vaccine. The CDC has also recommended that any patient with a history of anaphylaxis due to any cause (food, oral medications, bee sting, latex, etc.) be observed for 30 minutes after receiving the vaccine.

Which patients should speak to an allergist before receiving the vaccine?

In the vaccine trials, only patients with a history of severe allergic reaction associated with a vaccine and/or severe allergic reaction to any component of the vaccine were excluded. The vaccine should not be given to these patients under the FDA’s emergency use authorization, which is the current method for its use in the US. If you are unsure about your vaccine or PEG allergy history, an allergy consultation is recommended. In general, most patients allergic to one vaccine can receive other vaccinations safely.