The COVID-19 Task Force does not anticipate any contraindication for patients on allergen immunotherapy (AIT). The recommendations for 48 hours have not changed, but the rationale behind the 48 hours is to allow the clinician to recognize the cause should any reaction occur. There are no contraindications to giving an allergy shot and a vaccine on the same day.

An NIAID clinical trial is underway to study allergic reactions to the Moderna and Pfizer-BioNTech COVID-19 vaccines.  PDF icon A brief synopsis of the study is available herePDF icon A flyer about the study is available here.

AAAAI COVID-19 Response Task Force Guidance on Administration of COVID-19 Vaccines Related to Concerns of Allergic Reactions


The CDC has updated their guidance on administration of the SARS-CoV-2 mRNA vaccines with respect to pre-vaccine risks and post-vaccine reactions. The CDC has provided the following differentiation: 

  • Contraindication: Persons with a known (diagnosed) allergy to PEG, polysorbate or other component of a COVID-19 vaccine, or who have experienced a severe allergic reaction (e.g., anaphylaxis) after a previous COVID-19 vaccine dose have a contraindication to vaccination. 
    • Do not vaccinate
    • Consider referral to allergist/immunologist
    • Consider other vaccine alternative if age appropriate
  • Precaution: Persons with any immediate allergic reaction to other (non-COVID-19) vaccines or injectable therapies OR a non-severe immediate allergic reaction (onset < 4 hours) after a previous dose of COVID-19 vaccine fall into this category.
    • Risk assessment/counseling with physician prior to second dose
    • 30 minute observation period after vaccination
    • Consider referral to allergist/immunologist
    • Immediate allergic reaction is defined as any hypersensitivity-related signs or symptoms such as urticaria, angioedema, respiratory distress (e.g., wheezing, stridor), or anaphylaxis that occur within four hours following administration. 
  • May proceed with COVID-19 vaccine: Persons with a history of food, pet, insect, venom, environmental, oral medication (including the oral equivalent of an injectable medication) or latex allergies, or a family history of allergies. 
    • 30-minute observation period for anyone with a history of anaphylaxis (due to any cause)
    • 15 minute observation for all others
    • Vial stoppers of mRNA vaccines are not made with natural rubber latex 
    • The mRNA vaccines do not contain egg or gelatin 

Several studies are showing that individuals with an allergic reaction to their first mRNA COVID vaccine can safely receive a second dose.

  • A vaccine registry study from a single health system found that 86.7% tolerated a second dose when given under allergy clinic observation with antihistamine pre-treatment, and that PEG testing and challenges were not helpful, with a large number of false positives. (Ann Allergy Asthma Immunol, October 23, 2021)
  • This retrospective study of 66 patients with alleged allergic reactions to their first vaccine reported 80% successfully received their second vaccine. (Ann Allergy Asthma Immunol, October 23, 2021)
  • In this cohort study of 52,998 healthcare workers at the Massachusetts General Brigham Health System, self-reported high-risk allergy history was associated with an increased risk of self-reported allergic reactions after mRNA COVID-19 vaccination, but following the CDC guidelines, with allergist consultation, risk stratification, and shared decision-making, all employees were able to complete the 2-dose vaccine series. (JAMA Netw Open, October 26, 2021)

Other Reported Reactions


Thrombosis with Thrombocytopenia Syndrome (TTS) is a rare complication of vaccination with the J&J vaccine which presents with typical and atypical thromboses associated with thrombocytopenia.  Symptoms usually start between 6 and 15 days after vaccination. Most concerning is Cerebral Venous Sinus Thrombosis (CVST) which has been present in 54% of cases. All of the patients have required hospitalization, 66% have been admitted to the ICU, 17% have required post-hospital skilled nursing care and 15% have died (total of 9 patients confirmed as of 12/9/21). This can present with altered mental status, visual disturbances, hemiparesis, and seizures, and can rapidly progress from symptom onset to death. 

Although this is a very serious potential complication, it is also very rare. The overall reporting rate is 3.83 per million doses of J&J vaccine. The reporting rate varies among different age groups and sex.  Two-thirds of the cases have occurred in females. The group with the highest risk is 30-39 year-old females with a reporting rate of 10.60 per 1 million doses, closely followed by the 40-49-year-old female group with a reporting rate of 9.02/million doses. The reporting rate in both females and males over the age of 65 is low. The overall death reporting rate is 0.57/1 million doses but it 30-49-year old females, it is 1.80-1.93/1 million doses. Note: all cases have been reported through VAERS, so these may be underestimates.

At their meeting on December 16, the CDC’s Advisory Committee on Immunization Practices (ACIP) determined, based on the vaccine efficacy of the J&J vaccine, that the benefits still outweigh the risks, but that mRNA vaccines are recommended over the J&J based on higher efficacy and less serious adverse events. For example, in the highest risk group vaccination would prevent 3,729 hospitalizations with an expected 9 cases of TTS.



Mild episodes of myocarditis have been rarely reported following mRNA vaccination. Recent reports suggest that this complication may be more common with the Moderna vaccine ( Most of the patients have been discharged from the hospital within 1-2 days and only treated with steroids or anti-inflammatories. At 3 months FU, 90% are considered fully recovered. There has been one death reported from New Zealand, but details are not currently known. Like the TTS, the reporting rate varies with age and sex with the highest risk group 18-49-year-old males with a rate of 13 cases per 1 million doses. The rate for 18-49-year-old females is 2/million doses, and for 50-64-year-old males and females, 1/million doses. There have not been any cases reported in females over 65 years-old, and 1/million in males over 65.

In the 5-11-year-old age range, out of 7,141,428 doses administered, there have been 8 confirmed cases with another 5 being investigated.


Guillain-Barre Syndrome  

This has only occurred at a higher rate following the J&J vaccine. Mortality has been about 1%, 10% have required mechanical ventilation.  Most recover, although some nerve deficits may occur. This typically presents two weeks after vaccination.  Data presented at the July 17th meeting of the ACIP noted the highest rate in males over the age of 50 with 16 cases per 1 million doses. In females over 65, rates are 9/million doses.  Among females 50-64-years-old, and males and females 18-49-years-old, the rates are 5-7 per million doses, slightly over the expected background rate. The risk/benefit ratio favors vaccination for this complication because of the higher risk for hospitalization in those over 50.


Vaccine safety

  • This study from Denmark looked at the rate of adverse reactions after receipt of the bivalent booster in 1,740,417 adults. Findings: no significant increased rate of adverse events in the 28 days after receipt, although post-hoc analysis noted a rare but significant signal of myocarditis but only in female participants. (In CDC safety monitoring programs, the myocarditis was mostly in males). Safety of BA.4-5 or BA.1 bivalent mRNA booster vaccines: nationwide cohort study | The BMJ - July 25, 2023

  • This nationwide population-based study in Korea involved almost 4 million people who had received an mRNA COVID-19 vaccine without previous infection compared to similar numbers of prepandemic historical control. The risk of autoimmune connective tissue disorders was no higher in the vaccinated patients compared to the controls. Risk of autoimmune skin and connective tissue disorders after mRNA-based COVID-19 vaccination - Journal of the American Academy of Dermatology ( May 13, 2023

  • Safety Monitoring of mRNA COVID-19 Vaccine Third Doses Among Children Aged 6 Months–5 Years — United States, June 17, 2022–May 7, 2023 | MMWR (

  • Using data from the V-safe program, the CDC reviewed preliminary data on over 35,000 women who identified as pregnant after their vaccine. Data on almost 4,000 who participated in the pregnancy registry did not show any safety signals of concern, and outcomes were similar to studies on pregnant women before the pandemic. The CDC now recommends that all pregnant women be vaccinated. 
  • Results of safety monitoring from VAERS and V-safe after one month of vaccinations show over 90% of reactions were non-serious. Anaphylaxis rates (4.5 per million doses) remain in range of other vaccines. Female gender may be a risk factor for adverse reactions and anaphylaxis. (MMWR, February 26, 2021
  • A January 27, 2021 update from ACIP shows 50 cases of anaphylaxis following administration of the Pfizer BioNTech vaccine, after 10 million doses (5 per million) and 21 cases following administration of the Moderna vaccine (2.8 per million). 
  • There have now been reports of 196 deaths temporally associated with vaccination, 113 after Pfizer and 83 after Moderna; 66% were residents of long-term care facilities (LTCFs). Estimates of background mortality in LTCFs indicate an expected 11,440 deaths following vaccination. Mortality, then, was actually lower for vaccinated residents. 
  • Bottom line: This vaccine is very safe, and severe allergic reactions are exceedingly rare.