Originally posted January 18, 2021; most recently updated May 13, 2021
Q: What are the side effects of the COVID-19 vaccine?
A: The side effects have been similar to other routine vaccines – sore arm, redness, fatigue, fever, chills, headache, myalgia, arthralgia. The side effects are temporary and mostly mild or moderate. Side effects may be worse after the second dose in some.
Among the 22,000 patients who received the Pfizer-BioNTech COVID-19 vaccine as part of the phase 3 clinical trial, no serious allergic reactions to the vaccine were reported and there was no evidence of increased risk of allergic reactions to the vaccine. Similarly, in the 15,000 patients in the phase 3 Moderna COVID-19 vaccine trial, no serious allergic reactions to the vaccine were reported. After use of the vaccine began in the general population, severe allergic reactions were observed. These reactions are being closely monitored and the CDC has now estimated that the rate of anaphylaxis is approximately 5 in 1,000,000 after administration of 13.8 million doses of Pfizer-BioNTech and Moderna COVID-19 vaccines to the U.S., as compared to 1 in 1,000,000, which is the incidence of anaphylaxis associated with other vaccines. At this time there is no vaccine that is preferred in a patient with a history of severe allergic reactions. The National Institutes of Health is launching a study to understand these allergic reactions better, and the FDA and CDC are also closely monitoring.
Because of reports of anaphylactic reactions in people vaccinated outside of clinical trials, the additional following guidance has been put forward by the CDC:
- A severe allergic reaction to any vaccine or injectable therapy (intramuscular, intravenous or subcutaneous) is a precaution to vaccination at this time and patients should discuss the risks and benefits with an allergist/immunologist.
- Vaccine providers should observe patients after vaccination to monitor for the occurrence of immediate adverse reactions. Persons with a history of anaphylaxis are advised to wait 30 minutes and all other persons should wait at least 15 minutes.
Sites administering the vaccine should have healthcare personnel who are trained and qualified to recognize anaphylaxis and the medications and supplies necessary to assess and manage an allergic reaction.
Q: How do I report it if I have a problem or bad reaction after getting a COVID-19 vaccine?
A: The CDC and FDA encourage the public to report possible side effects (called adverse events) to the Vaccine Adverse Event Reporting System (VAERS). This national system collects these data to look for adverse events that are unexpected, appear to happen more often than expected, or have unusual patterns of occurrence. Health care providers are required to report certain adverse events following vaccination to VAERS. Health care providers also have to adhere to any revised safety reporting requirements according to the FDA’s conditions of authorized use throughout the duration of any Emergency Use Authorization; these requirements are posted on the FDA’s website.
The CDC is also implementing a new smartphone-based tool called v-safe to check in on people’s health after they receive a COVID-19 vaccine. When you receive your vaccine, you should also receive a v-safe information sheet telling you how to enroll in v-safe. If you enroll, you will receive regular text messages directing you to surveys where you can report any problems or adverse reactions you have after receiving a COVID-19 vaccine. ACAAI recommends that patients opt into the v-safe program to help all of us understand any possible side effects from the vaccines.
Q: What is the safety testing that has been done on COVID-19 vaccines? How do we know it is safe long-term?
A: The safety follow-up for COVID-19 vaccines is essentially the same as for all vaccine trials: two years of follow-up in phase 3 clinical trials. Given the importance of the vaccine in ending the current pandemic, both mRNA COVID-19 vaccines were authorized under Emergency Use Authorization by the FDA, and follow-up in the trials is ongoing.
We do not yet know long-term safety profile of these vaccines. It is reassuring that long-term side effects with vaccines are quite rare and severe reactions typically occur within days to weeks after administration. Although this is the first time an mRNA vaccine has been used in the general population, they have been used in trials for rabies, influenza, cytomegalovirus, and Zika and no significant safety concerns were seen.
Q: Should pregnant or breastfeeding women receive the COVID-19 vaccine?
A: Based on how these vaccines work in the body, experts believe they are unlikely to pose a risk for people who are pregnant. However, there are currently limited data on the safety of COVID-19 vaccines in pregnant people.
Clinical trials that study the safety of COVID-19 vaccines and how well they work in pregnant people are underway or planned. Vaccine manufacturers are also collecting and reviewing data from people in the completed clinical trials who received vaccine and became pregnant. Studies in animals receiving a Moderna, Pfizer-BioNTech, or J&J/Janssen COVID-19 vaccine before or during pregnancy found no safety concerns in pregnant animals or their babies.
CDC and the Federal Drug Administration (FDA) have safety monitoring systems in place to gather information about COVID-19 vaccination during pregnancy and will closely monitor that information. Early data from these systems are preliminary, but reassuring. These data did not identify any safety concerns for pregnant people who were vaccinated or for their babies. Most of the pregnancies reported in these systems are ongoing, so more follow-up data are needed for people vaccinated just before or early in pregnancy. We will continue to follow people vaccinated during all trimesters of pregnancy to understand effects on pregnancy and babies.
The Moderna and Pfizer-BioNTech vaccines are mRNA vaccines that do not contain the live virus that causes COVID-19 and therefore, cannot give someone COVID-19. Additionally, mRNA vaccines do not interact with a person’s DNA or cause genetic changes because the mRNA does not enter the nucleus of the cell, which is where our DNA is kept.
The J&J/Janssen COVID-19 Vaccine is a viral vector vaccine, meaning it uses a modified version of a different virus (the vector) to deliver important instructions to our cells. Vaccines that use the same viral vector have been given to pregnant people in all trimesters of pregnancy, including in a large-scale Ebola vaccination trial. No adverse pregnancy-related outcomes, including adverse outcomes that affected the infant, were associated with vaccination in these trials.
Clinical trials for the COVID-19 vaccines currently authorized for use under an Emergency Use Authorization in the United States did not include people who are breastfeeding. Because the vaccines have not been studied on lactating people, there are no data available on the:
- Safety of COVID-19 vaccines in lactating people
- Effects of vaccination on the breastfed baby
- Effects on milk production or excretion
Based on how these vaccines work in the body, COVID-19 vaccines are thought not to be a risk to lactating people or their breastfeeding babies. Therefore, lactating people can receive a COVID-19 vaccine. Recent reports have shown that breastfeeding people who have received COVID-19 mRNA vaccines have antibodies in their breastmilk, which could help protect their babies. More data are needed to determine what protection these antibodies may provide to the baby
Q: Do I need to worry about an increase in Multisystem Inflammatory Syndrome in Children (MIS-C) receiving COVID-19 vaccine?
A: One of the reasons to perform vaccine trials in children is to make sure that they do not have any side effects that are pediatric-specific. There are also cases of multisystem inflammatory syndrome (MIS) in young adults so ongoing vaccination in young adults may allow us to know whether this complication occurs in vaccinated individuals. Unfortunately, there is no known biomarker to predict an immune response that leads to MIS-C. It is also possible that protection from COVID-19 by vaccination will also protect against its sequelae, including MIS-C.
Q: I have asthma and I’m on inhaled corticosteroids. I heard they depress the immune system. Can I get the COVID-19 Vaccine?
A: There are no data to suggest any major degree of weakening of the immune system due to inhaled corticosteroids in use for asthma. It is important that your asthma is under control. There is no contraindication to receiving the COVID-19 vaccine while on inhaled corticosteroids.
Q: I have allergic rhinitis and I’m on intranasal corticosteroids. I heard they depress the immune system. Can I get the COVID-19 vaccine?
A: There are no data to suggest any major degree of weakening of the immune system due to intranasal corticosteroids in use for allergic rhinitis and therefore there is no contraindication to receiving the COVID-19 vaccine while on inhaled corticosteroids.
Q: I have severe asthma and take oral corticosteroids for asthma. I understand oral corticosteroids can weaken my immune system. Should I take the COVID-19 vaccine?
A: There is no contraindication to receiving the COVID-19 vaccine while on oral corticosteroids. Presently we don’t know if regular oral corticosteroid use will limit the effectiveness of the COVID-19 vaccine as there is a potential for reduced immune responses to the vaccine. Much depends on the daily dose and for how long the patient has been on regular corticosteroids. Low-dose alternate day with short acting preparations such as prednisone probably have minimal if any depression of the immune system. Also, there is limited safety data with the COVID-19 vaccine with patients on regular oral corticosteroids at this time.
Q: I had a burst of corticosteroids for asthma. How long do I have to wait for the COVID-19 vaccine?
A: There are no data on effects of systemic corticosteroids and on immune response to COVID-19 vaccines. The optimal timing for COVID-19 vaccine following corticosteroids is unknown. mRNA vaccines such as COVID-19 vaccines do not represent a danger to immunocompromised persons and generally should be administered as recommended for healthy persons.
Q: Can I take the vaccine if I am on biologics for asthma?
A: The ACAAI recommends that the COVID-19 vaccine and a biologic not be given the same day since, if there is a reaction after the second injection (vaccine or biologic) is given, it may be difficult to decide which one it was the inciting agent. We suggest separating these injections by a minimum of 24 hours. There is no reason to stop a biologic until the patient completes the course of the COVID-19 vaccinations.
Q: Can I take the vaccine if I am on allergen immunotherapy?
A: The ACAAI recommends that the COVID-19 vaccine and allergen immunotherapy (AIT) not be given the same day since, if there is a reaction after the second injection (vaccine or AIT) is given, it may be difficult to decide which one it was the inciting agent. We suggest separating these injections by a minimum of 24 hours. There is no reason to stop AIT until the patient completes the course of the COVID-19 vaccinations.