COVID-19 vaccine: Frequently asked questions – Updated 2/4/21

| January 18, 2021

COVID-19 vaccine: Frequently asked questions – Updated 2/4/21

Updated 2/4/2021


This FAQ document is provided to physicians by ACAAI to assist in answering patient questions about COVID-19 vaccines. It also provides additional information for clinicians. These recommendations are based on best knowledge to date but could change at any time, pending new information and further guidance from the Food and Drug Administration (FDA) or Centers for Disease Control and Prevention (CDC).



Q: How does the COVID-19 vaccine work?

A: Preventing infection is essential to ending the current pandemic. A COVID-19 vaccine helps to generate immunity to the SARS-CoV-2 virus (the virus that causes COVID-19), decreasing the risk of infection with exposure. Currently, two COVID-19 vaccines are available in the United States. One is made by Pfizer/BioNTech and the other by Moderna, and therefore, the vaccines are often referred to as the Pfizer vaccine and the Moderna vaccine respectively. Both contain messenger RNA that encodes the spike protein that the SARS-CoV-2 virus uses to attach to human cells during infection. When muscle cells take up the mRNA and express the spike protein, it stimulates your immune system to make antibodies against it. This makes you  less susceptible to contracting the SARS-CoV-2 virus. Both vaccines require two doses, three or four weeks apart in order to achieve an optimal immune response.


Q: Can someone get COVID-19 from the vaccine?

A: It is not possible to get COVID-19 from any of the available vaccines or those currently under investigation. The mRNA vaccines encode only the information for the spike protein of the virus. Other vaccine candidates use inactivated virus, parts of the virus (e.g., the spike protein) or a gene from the virus. None of these can cause COVID-19. Vaccines undergo rigorous testing through clinical trials to ensure they are safe and effective for those who receive them. The COVID-19 vaccines are being held to the same rigorous safety and effectiveness standards as all other types of vaccines in the United States.

Most side effects, if any, are similar to other vaccines, including soreness at the injection site, muscle aches, fatigue, or mild fever.


Q: Are there any safety concerns with the new technologies (mRNA and nanotechnology) being used in the development of COVID-19 vaccines?

A: There are no known additional risks of mRNA vaccines or lipid nanoparticles. Live attenuated viral vaccines, such as measles vaccine, induce an immune response by using a virus that can replicate but not cause infection. mRNA vaccines, on the other hand, simply give the body instructions to produce one very specific part of a virus – in this case, the spike protein, which induces an immune response. Because mRNA is broken down very quickly in the human body, the mRNA is wrapped in lipid nanoparticles to protect it and allow it to enter cells. Once it gets into the cells to deliver the instructions, the mRNA breaks down very quickly. It does not get into the nucleus of the cell, is not inserted into the genome and it does not change your DNA.


Q: How effective are the COVID-19 vaccines currently available in the United States? Are there advantages or disadvantages to receiving the Pfizer vs. Moderna vaccine? If patients have a choice, which vaccine should they receive?

A: This STAT article provides a good side-by-side comparison of the Pfizer and Moderna vaccines. The College also has a helpful comparison of the two vaccines.

The vaccines are both effective. In the phase 3 clinical trial data published in the New England Journal of Medicine, both the Pfizer and Moderna vaccines lowered the chance of developing Covid-19 by around 95% as compared with placebo. This is remarkably effective when compared to the flu vaccine, which is typically 40-60% effective.

An important caveat to the favorable efficacy results in the clinical trials is that the performance of the vaccines in clinical practice – the effectiveness – may be different. Although the participants in both studies included people at high risk for Covid-19 complications, participants had to be clinically stable and sufficiently healthy to come in for their study visits. We do not yet know how effective the vaccines will be in sicker populations, such as frail elderly people living in nursing homes or the severely immunocompromised. Population-based studies that include hundreds of thousands of people ultimately will give us a better sense of these “real world” data.


Q: Should patients still get the vaccine for influenza this year, and what is the recommended interval in relationship to receiving the COVID-19 vaccine?

A:  Yes, it is very important to get the influenza vaccine, particularly this season when both influenza viruses and SARS-CoV-2 are circulating and can cause similar symptoms. We still do not know how these two viruses will interact, but people can get infected with both, and this will likely cause more severe disease and possibly death. Reducing the number of people who get severe influenza and require hospitalization will also help ensure that the health care system, hospitals and intensive care units will not be overwhelmed should there be an increase in COVID-19 cases this fall and winter. The Centers for Disease Control and Prevention (CDC) recommends that COVID-19 vaccine should be administered alone with a minimum interval of 14 days before or after administration of any other vaccines due to lack of data on safety and efficacy of COVID-19 vaccines given simultaneously with other vaccines.



Q: Are there any contraindications to getting a COVID-19 vaccine?

A: According to the CDC, people who have had an immediate allergic reaction, even if it was not severe, to a vaccine or injectable therapy for another disease, should consult their physicians to determine if they should get a COVID-19 vaccine. The COVID-19 vaccines should not be given in combination with other vaccines right now, and the CDC recommends 14 days between receiving the COVID-19 vaccine and other vaccines.

Following reports of a small number of  patients experiencing anaphylaxis after getting a COVID-19 vaccine, the CDC issued guidance related to the COVID-19 vaccines and severe allergic reactions. ACAAI also published guidance on the risk of allergic reactions to mRNA COVID-19 vaccines.

Patients who have an immediate (<4 hours) or severe allergic reaction to the first dose of the COVID-19 vaccine should not receive the second dose.

The mRNA COVID-19 vaccines should not be administered to individuals with a known history of a severe allergic reaction to any component of the vaccine. Although the specific vaccine component causing anaphylaxis has not been identified, polyethylene glycol (PEG) is one of the ingredients in these vaccine products and has been known to cause anaphylaxis.

Patients who have had COVID-19 and received monoclonal antibodies or convalescent serum to treat COVID-19 should wait 90 days before getting the vaccine.


Q: How many doses of the COVID-19 vaccine will be needed?

A: Both of the currently available COVID-19 vaccines in the U.S. require two doses. All but one of the COVID-19 vaccines currently in Phase 3 clinical trials in the U.S. need two doses to be effective.


Q: What happens when someone is late getting their second booster dose?

A: The Pfizer COVID-19 vaccine dosing schedule recommends the second dose be given 21 days after the first dose (with a 4-day grace period). The Moderna vaccine schedule recommends the second dose be given 28 days after the first shot. If it is not feasible to adhere to the recommended interval, the second dose of Pfizer-BioNTech and Moderna COVID-19 vaccines may be scheduled for administration up to 6 weeks (42 days) after the first dose.


Q: What happens when someone fails to get the second dose of the vaccine?

A: The efficacy of a single dose of the approved vaccines has not been studied. However, it is likely that a person will not be fully protected against COVID-19. Protection offered by a single dose of vaccine has been estimated to be at 50%, and the second dose increases this to more than 90%.


Q: Do both doses need to be with the same vaccine? 

A: Yes, if at all possible. According to the CDC, every effort should be made to determine which vaccine product was received as the first dose, in order to ensure completion of the vaccine series with the same product. In exceptional situations in which the first-dose vaccine product cannot be determined or is no longer available, any available mRNA COVID-19 vaccine may be administered at a minimum interval of 28 days between doses to complete the mRNA COVID-19 vaccination series. If two doses of different mRNA COVID-19 vaccine products are administered, no additional doses of either product are recommended.


Q: If someone already had COVID-19 and recovered, do they still need to get a vaccine when it’s available?

A: There is not enough information currently available to say if or for how long after infection someone is protected from getting COVID-19 again; this is called natural immunity. Early evidence suggests natural immunity from COVID-19 may not last very long, but more studies are needed to better understand this.

According to the CDC, COVID-19 vaccination should be offered to you regardless of whether you already had COVID-19 infection. You are not required to have an antibody test before you are vaccinated.

However, anyone currently infected with COVID-19 should wait to get vaccinated until after their illness has resolved and after they have met the criteria to discontinue isolation.

Additionally, current evidence suggests that reinfection with the virus that causes COVID-19 is uncommon in the 90 days after initial infection. Therefore, people with a recent infection may delay vaccination until the end of that 90-day period if desired.


Q: Will my nasal PCR swab or antigen testing be positive after I get the COVID-19 vaccine?

A: The Covid-19 vaccines will not influence the results of PCR or antigen testing for the disease. The vaccines generate antibodies to SARS-CoV-2, which are directed at the spike protein. Some available serologic assays test for this antibody; others do not. The manufacturers of the individual antibody tests should be able to provide this information, and it is often listed in the package insert.


Q: What if someone gets a COVID-19 vaccine and subsequently gets COVID-19 before receiving the second COVID-19 vaccine? Should they get the second dose?

A: When to get the booster is multifactorial and depends upon the medications used to treat your COVID-19 infection. This decision should be made after discussion with your provider.

According to the CDC, prior receipt of an mRNA COVID vaccine should not affect treatment decisions including the use of monoclonal antibody therapy, convalescent plasma, antiviral treatment or corticosteroid administration.

Currently, there are no data on the safety and efficacy of mRNA COVID-19 vaccines in persons who received monoclonal antibodies or convalescent plasma as part of COVID-19 treatment. Based on the estimated half-life of such therapies as well as evidence suggesting that reinfection is uncommon in the 90 days after initial infection, vaccination should be deferred for at least 90 days, as a precautionary measure until additional information becomes available, to avoid potential interference of the antibody therapy with vaccine-induced immune responses. This recommendation applies to persons who receive passive antibody therapy before receiving any vaccine doses. It also applies to  those who receive passive antibody therapy after the first dose but before the second dose, in which case the second dose should be deferred for at least 90 days following receipt of the antibody therapy.

If no monoclonal antibody therapy is administered, then a booster dose can be administered after recovery from COVID-19 and the isolation period has ended.


Q: Is a history of receiving injected dermal fillers a contraindication to getting the COVID-19 vaccine?

A: Having had dermal filler injections is not a contraindication for mRNA vaccine administration. Persons who have received dermal fillers may develop swelling at or near the site of the filler injection following administration of an mRNA COVID 19 vaccine. The symptom is temporary and treatable and has been seen with other vaccines.


Q: Can someone get a COVID-19 vaccine if they have an underlying medical condition such as HIV or another immunocompromising condition, autoimmune condition, a history of Guillain-Barre syndrome or Bell’s palsy? 

A: mRNA COVID-19 vaccines may be administered to persons with underlying medical conditions who have no contraindications to vaccination. In fact, clinical trials demonstrated similar safety and efficacy profiles in persons with some underlying medical conditions, including those that place them at increased risk for severe COVID-19. The risks and benefits should be discussed with the individual patient depending on their underlying medical condition.


Q: What if someone received the vaccination during cancer treatment and the treatments are now over?  Should they get vaccinated again?

A: Revaccination is not currently recommended after immune competence is regained in persons who received mRNA COVID-19 vaccines during chemotherapy or treatment with other immunosuppressive drugs.


Q: Do individuals need to wear a mask and avoid close contact with others if they have received two doses of the vaccine?

A: Yes. While experts learn more about the protection that COVID-19 vaccines provide under real-life conditions, it will be important for everyone to continue using all the tools available to us to help stop this pandemic, like covering your mouth and nose with a mask, washing hands often, and staying at least 6 feet away from others. Together, COVID-19 vaccination and following the CDC’s recommendations for how to protect yourself and others will offer the best protection from getting and spreading COVID-19. Experts need to understand more about the protection that COVID-19 vaccines provide before deciding to change recommendations about steps everyone should take to slow the spread of the virus. Other factors, including how many people get vaccinated and how the virus is spreading in communities, will also affect this decision.


Q: When will the need for masking and social distancing be over?

A: There is not enough information currently available to say if or when the CDC will stop recommending that people wear masks and avoid close contact with others to help prevent the spread of the virus that causes COVID-19. Experts need to understand more about the protection that COVID-19 vaccines provide before making that decision. Other factors, including how many people get vaccinated and how the virus is spreading in communities, will also affect this decision.


Q: Does immunity after getting COVID-19 last longer than protection from COVID-19 vaccines?

A: The protection someone gains from having an infection (called natural immunity) varies depending on the disease, and it varies from person to person. Since this virus is new, we don’t know how long natural immunity might last. Some early evidence seems to suggest that natural immunity may not last very long.

We do not know how long protection will last following vaccination, but it will be critically important to measure long-term protection (at least 2 years) in the phase 3 trials and in other groups prioritized for early vaccination. We are still learning about the duration of protection following infection with SARS-CoV-2, and it is too early to tell how long protection will last. There have already been cases where individuals have been shown to be infected twice, but most often the second illness was mild or without any symptoms. This is what we would expect with an immune response that protects against disease but not infection.


Q: Will the vaccines protect against the new COVID-19 variant strain (e.g. B.1.1.7 found in the U.K. and now U.S.)?

A: Currently there is limited information on how effective the mRNA vaccines will be against emerging strains of SARS-CoV-2. Both clinical trials preceded the identification of the major variants present now in multiple countries around the world. Preliminary studies (not yet peer reviewed and published) suggest that the vaccines are protective but might be more protective against some of the variants than others (N501Y variant, 501Y.V2 variant, other variants). An important limitation of these studies (which used samples from immunized or recovered people in the lab to assess neutralization) is that protection afforded by vaccination is more complex than simply measuring antibody responses. Molecular sequencing of the viruses from incident cases of Covid-19 that occur after vaccination will be important to help understand this important issue.

From a practical perspective, the discovery of these variants does not change the basic recommendations for vaccination. Specifically, right now it is not recommended that people wait for a new or changed vaccine in the hope that it will be more effective against emerging SARS-CoV-2 variants.


Q: What percentage of the population needs to get vaccinated to achieve herd immunity to COVID-19?

A: Herd immunity is a term used to describe when enough people have protection – either from previous infection or vaccination – that it is unlikely a virus or bacteria can spread and cause disease. As a result, everyone within the community is protected even if some people don’t have any immunity themselves. The percentage of people who need to have protection in order to achieve herd immunity varies by disease. Experts estimate that at least 70% of the population would need to have immunity, either through infection or vaccination, to achieve herd immunity to COVID-19.


Q: Will there be enough vaccine for everyone?

A: The goal is for everyone to be able to receive a COVID-19 vaccine as soon as possible, but given the current limited supply, a phased approach is being planned. The federal government is investing in helping vaccine manufacturers increase their ability to quickly make and distribute a large amount of the COVID-19 vaccine. As vaccine becomes available, vaccination sites will be opened, including doctors’ offices, retail pharmacies, hospitals, and federally qualified health centers.


Q: How do patients protect themselves from getting COVID-19 if they have not received the vaccine?

A: Patients should cover their mouth and nose with a mask when around others, avoid close contact with people who are sick, stay six feet away from others, avoid crowds, and wash their hands often. Get more information about these and other steps you can take to protect yourself and others from COVID-19.


Q: Should children get the COVID-19 vaccine?

A: Children were not included in the initial phase 3 trials and there is currently no approved vaccine for children under 16 years. The Pfizer vaccine is FDA-approved for patients 16 years and older, while the Moderna vaccine is FDA-approved for patients 18 years and older. Trials including children age 12-17 are ongoing.

While children are less likely to develop severe disease and die from COVID-19, there are several reasons for ensuring there is a vaccine safe for children. Although rare, some children may develop severe disease or die from COVID-19. Children have also developed a severe inflammatory syndrome, called multisystem inflammatory syndrome, associated with the virus. Further, children may be important transmitters of SARS-CoV-2 and vaccinating them could be important in controlling the pandemic. Finally, having a safe vaccine for children will build confidence toward opening up schools and learning centers for in-person education.


Q: Will there be a vaccine available for children before the 2021-22 school year?

A: This will depend on the results of the trials of the vaccine in adolescents and children that are underway now. Based on the current pace of research, it is potentially achievable to have a vaccine for at least some age groups of children and adolescents before the 2021-22 school year begins.


Q: Can COVID-19 vaccine be co-administered with other childhood or adolescent immunizations?

A: Until we have a COVID-19 vaccine for children, we need to focus on getting children caught up and keeping them up to date on routinely recommended vaccines. Under-vaccinated children will be at greater risk of other vaccine preventable illnesses such as measles, pertussis, and influenza unless they are fully vaccinated.

Administration of the COVID-19 vaccine with other childhood or adolescent immunizations has not yet been tested. There are very few vaccines in which co-administration with other vaccines is problematic. This topic needs to be studied, especially in the youngest children who receive vaccines at so many of their visits. Due to lack of data on safety and efficacy of the vaccine administered simultaneously with other vaccines, the CDC recommends COVID-19 vaccine should be administered alone with a minimum interval of 14 days before or after administration with any other vaccines.

Note the Pfizer vaccine is FDA-approved for patients 16 years and older, while the Moderna vaccine is FDA-approved for patients 18 years and older.


Q: Will the vaccine be required for school entry?

A: When a vaccine is shown to be safe and effective in children, health authorities, including the CDC and the American Academy of Pediatrics, will make recommendations on when and how children should receive the vaccine. However, state governments set requirements for which vaccines are needed for school entry.


Q: How much will the COVID-19 vaccine cost?

A: There is no cost. The shots are free to everyone, even if you don’t have health insurance. The federal government is covering the cost.



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 have been observed. After vaccination of more than two million health care workers, the incidence of anaphylaxis associated with the Pfizer SARS-CoV-2 mRNA vaccine appeared to be approximately 10 times as high as the incidence reported with previous vaccines, at approximately 10 in 1,000,000, as compared 1 in 1,000,000, which is the incidence of anaphylaxis associated with other vaccines. The CDC has now estimated that it is closer to 5 in 1,000,000. The incidence of anaphylaxis associated with the Moderna vaccine has been estimated at 2.5 in 1,000,000.

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 is proposed:

  • A severe allergic reaction to any vaccine or injectable therapy (intramuscular, intravenous or subcutaneous) is a precaution to vaccination at this time.
  • 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.


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 in to 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.


Q: Should pregnant or breastfeeding women receive the COVID-19 vaccine?

A: Pregnancy and breastfeeding are not contraindications to receiving COVID-19 vaccine; however, there are no safety data in pregnant women or infants at this time. While these vaccines were not specifically tested in breastfeeding women, it is not likely (based on the mechanisms of action of the vaccines in U.S. trials) that there would be any risk to the child.

There is increased risk of severe COVID-19 illness (ICU admission, mechanical ventilation and death) in pregnant women and possibly an increased risk of adverse pregnancy outcomes, such as preterm birth. If a woman is part of a group (e.g., health care personnel) who is recommended to receive a COVID-19 vaccine and is pregnant, she may choose to be vaccinated. It is recommended that the decision be discussed with her health care provider so an informed decision can be made.


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.


Q: What recommendations do you have for patients with underlying medical conditions, such as weakened immune systems, autoimmune conditions, and those who previously had Guillain-Barre syndrome (GBS) or Bell’s palsy?

A: The CDC has up-to-date COVID-19 vaccine recommendations for these patients. GBS within 6 weeks of tetanus toxoid or influenza vaccine is a precaution for receiving the same vaccine. GBS not associated with a vaccine is not a contraindication nor precaution for receiving the COVID-19 vaccine. Bell’s palsy is not a contraindication either.



Q: What is the College’s approach to a COVID-19 vaccine?

A: The College strongly recommends frontline workers, essential workers, and patients with high-risk medical conditions receive the COVID-19 vaccine in order to protect patients and community members they come into contact with.

The College recognizes that recommending vaccination to health care workers and patients is a vital step in creating a healthier community and finding a path back to normalcy. However, our team of experts are hard at work ensuring the vaccines are is effective and the benefits outweigh any potential risks prior to administering it to members or patients.


The following information is provided for clinicians.

NOTE – This was on the CDC website and may be helpful to clinicians:

Health care personnel or health departments in the United States can request a consultation from the Clinical Immunization Safety Assessment COVID vax project for a complex COVID-19 vaccine safety question about an individual patient residing in the United States not readily addressed by CDC guidance.


Q: What are the ingredients in the Pfizer-BioNTech COVID-19 Vaccine?


  1. The active ingredient is a nucleoside-modified messenger RNA (modRNA) encoding the viral spike (S) glycoprotein of SARS-CoV-2.
  2. Inactive ingredients:

Lipids ((4-hydroxybutyl)azanediyl)bis(hexane-6,1-diyl)bis(2-hexyldecanoate), [(polyethylene glycol [PEG])-2000]-N,N-ditetradecylacetamide, 1,2-distearoyl-sn-glycero-3-phosphocholine, and 0.2 mg cholesterol)

Electrolytes potassium chloride, monobasic potassium phosphate, sodium chloride, dibasic sodium phosphate dihydrate

Sugar (sucrose)

The diluent, added to the vaccine for administration, is saline (Sodium Chloride)


Q: What are the ingredients in the Moderna COVID-19 Vaccine?  


  1. Messenger ribonucleic acid (mRNA)
  2. Inactive Ingredients:

Lipids (SM-102, polyethylene glycol [PEG] 2000 dimyristoyl glycerol [DMG], cholesterol, and 1,2-distearoyl-sn-glycero-3-phosphocholine [DSPC])


Tromethamine hydrochloride

Acetic acid

Sodium acetate

Sugar (sucrose)


Q: What is PEG?

A: Polyethylene glycol (PEG) is a common, water-soluble ingredient in a wide variety of commercial products including some vaccines and more than 1,000 FDA approved medications. It is the primary ingredient in commonly used colonoscopy preparations (Golytely) or constipation treatment (Miralax) as well as in IV medications such as PEGylated medications. It is also in ultrasound gel and injectable steroid injections such as methylprednisolone acetate. Reactions to polyethylene glycol are exceedingly rare but anaphylaxis has been reported. Polysorbate is structurally related to PEG and cross-reactivity can occur so polysorbate allergy is also considered a contraindication to receiving the vaccine.


Contact dermatitis to PEG

A history of contact dermatitis (rash with exposure or history of positive patch testing) to PEG or to a related compound including polysorbate is not a contraindication to getting the vaccine. No cross reactivity has been demonstrated between propylene glycol and PEG derivatives.


Systemic reactions to PEG

The most commonly known clinical use of polyethylene glycol is PEG 3350 in colonoscopy preparations or constipation treatment (e.g. Miralax). However, PEG and structurally similar polysorbate compounds can be found in vascular graft materials, surgical gels, PEGylated medications, household and industrial compounds, and as an excipient in a multitude of other medications, both injectable and oral.

A recent review of published case reports and case series in the literature by Garvey et al. found 37 cases of PEG hypersensitivity since 1977. A review of the FDA data by Stone et al adds a large number of additional cases that may not have been noticed in the medical literature. Their data suggests an average of four cases per year of PEG-associated anaphylaxis during colonoscopy preparation or laxative use are reported to the FDA. The review of FDA adverse event data focused only on drugs that contained pure PEG 3350 at concentrations of grams per dose. To determine clinical reactivity to macrogols, including PEG and polysorbate containing products, Stone et al used a combination of skin prick, intradermal and challenge testing with standard methodologies. Little is known about cross reactivity among the different molecular weights of PEG for both contact dermatitis and immediate hypersensitivity reactions, but it is likely that molecular weight is an important factor. The molecular weight of PEG in the Pfizer and Moderna COVID vaccines is 2,000.

Patch testing may evaluate for contact dermatitis to PEG in personal products. Chemotique has a commercially available PEG patch test (Molecular weight PEG 400). Immediate hypersensitivity reactions are typically evaluated by skin prick and intradermal tests, which to date have not been standardized for PEG. There are some testing protocols that have been published in the medical literature that can be considered specifically for the evaluation of IgE mediated allergy to PEG with the caveat that a negative skin test result does not rule out allergy: Skin testing could be negative because it’s a false negative (using non-irritating skin test concentrations) or because the individual doesn’t have an IgE mediated allergy or because the allergic reaction to the first dose was related to complement activation-related pseudoallergy (CARPA).


CDC COVID-19 Frequently Asked Questions

CDC issued guidance related to the COVID-19 vaccines and severe allergic reactions

CDC Vaccination Considerations for Persons with Underlying Medical Conditions

CDC Discontinuation of Isolation for Persons with COVID-19 Not in Healthcare Settings

Atrium Health, Charlotte, NC COVID-19 vaccine FAQ – accessed 12/15/20

FDA COVID-19 Frequently Asked Questions

Johns Hopkins COVID-19 Vaccine Frequently Asked Questions

Branswell H. A side-by side comparison of the Pfizer/BioNTech and Moderna vaccines.

STAT News. – accessed 12/15/20

Fisher Contact Dermatitis 9the Edition

Stone CA Jr, Liu Y, Relling MV, Krantz MS, Pratt AL, Abreo A, Hemler JA, Phillips EJ. Immediate Hypersensitivity to Polyethylene Glycols and Polysorbates: More Common Than We Have Recognized. J Allergy Clin Immunol Pract. 2019 May-Jun;7(5):1533-1540.e8. doi: 10.1016/j.jaip.2018.12.003. Epub 2018 Dec 14. PMID: 30557713; PMCID: PMC6706272.