What you need to know about the SARS-COV-2 vaccine and allergies

CDC's ACIP Expands on Precautions and Contraindications for Pfizer Vaccine

What to know:

“Severe allergic reaction (e.g., anaphylaxis) to any component of the Pfizer-BioNTech COVID-19 vaccine is a contraindication to vaccination listed in the prescribing information. Anaphylactic reactions in persons outside of clinical trials have been reported. While these reports are further investigated, CDC considers a history of severe allergic reaction (e.g., anaphylaxis) to any other vaccine or injectable therapy (e.g., intramuscular, intravenous, or subcutaneous) as a precaution but not a contraindication to vaccination. In persons who report a history of anaphylaxis to another vaccine (i.e., any other vaccine besides the Pfizer-BioNTech COVID-19 vaccine) or injectable therapy, a risk assessment should be conducted to determine type of reaction and certainty of information.

For example, whether the medication was administered by injection or another route or whether the reaction constituted a severe allergic reaction (e.g., required use of epinephrine [EpiPen®, etc.], resulted in hospitalization). These persons may still receive vaccination, but they should be counseled about the unknown risks of developing a severe allergic reaction and balance these risks against the benefits of vaccination. A history of mild allergic reaction to a vaccine or injectable therapy, such as urticaria alone without signs or symptoms of anaphylaxis, is not a contraindication or precaution to Pfizer-BioNTech COVID-19 vaccination. In addition, allergic reactions (including severe allergic reactions) not related to vaccines or injectable therapies (e.g., food, pet, venom, environmental, or latex allergies; oral medications [including the oral equivalents of injectable medications]) are not a contraindication or precaution to vaccination with Pfizer-BioNTech COVID-19 vaccine.”

Additional discussion about clinical considerations for use of the vaccine can be found here.

Allergists need to know that the CDC/ACIP/FDA and NIAID are aware of the reactions that have occurred and are actively working, along with leadership of the AAAAI, to determine the cause for these reactions, and developing protocols to help you deal with them.

Added Precautions

  1. The CDC has also issued guidelines on precautions and management of anaphylaxis to sites that administer the vaccines.
  2. Recommendations are to avoid any other vaccinations for 14 days before or after the SARS-CoV-2 vaccine, but if you have had another vaccine within that 14 day window, don’t wait to get this vaccine.
  3. Recommendations are to defer vaccination for 90 days after receiving convalescent plasma or monoclonal antibody treatment for COVID-19.

About the Moderna Vaccine:

This vaccine has been granted an EUA and approval from the CDC/ACIP.

Results from the clinical trials are very similar in efficacy and safety compared to the Pfizer vaccine. The FDA
Briefing Document can be found here. This document presents both interim analysis using a data cutoff of
November 7, with a median follow-up of 7 weeks post-dose one, and the final scheduled analysis from a data cutoff of November 21, with a median follow-up >2 months post-dose two. This summary covers the final scheduled analysis.


The most common adverse reactions: injection site pain (91.6%), fatigue (68.5%), muscle pain (59.6%), joint pain (44.8%), chills (43.4%), fever (14.8%). Most of these were mild to moderate, began on day 1-2 and lasted 2 days. A small number of participants reported systemic reactions longer than 7 days, but there was no difference between vaccinated and placebo groups. Lymphadenopathy (axillary) was reported in 21.4% of vaccine recipients <65 years of age, and 12.4% in those >65 years of age, compared to 7.5% and 5.8% in placebo in those age groups respectively. Severe adverse reactions occurred in 0.2% to 9.7% of participants, and were more frequent after the second dose and less common in those 65 years of age and older. Hypersensitivity adverse events were slightly greater in the vaccine group (1.5%) compared to the placebo group (1.1%). There were no anaphylactic or severe hypersensitivity reactions. This vaccine also contains PEG in the lipid capsule. Serious adverse events were low (1.0%) without meaningful imbalances between study arms. Other than the differences in the age groups and reactogenic reactions, there were no safety differences with respect to race, ethnicity, gender or pre-existing conditions.


Vaccine efficacy was 94.1% (95% CI 89.3%, 96.8%) with 11 cases of COVID-19 in the vaccine group and 185 cases in the placebo group. Unlike the interim data, the vaccine efficacy when stratified by age group was 95.6% (95% CI 90.6%, 97.9%) for participants 18 to <65 years of age and 86.4% (95% CI 61.4%, 95.5%) for participants 65 years of age or older. Other than the age group difference, there were no vaccine efficacy differences based on race, ethnicity, gender or medical comorbidities associated with high risk for severe COVID-19. Vaccine efficacy against severe COVID-19: 30 cases in the placebo group, 0 in the vaccine group. Vaccine efficacy after the first dose was 80.2% (95% CI, 55.2%, 92.5%) in the 2,000+ patients who only received one dose, but these patients were only followed for 28 days.

*Efficacy against asymptomatic infection: preliminary data only, NP swabs were collected pre-dose one and pre-dose two. Number of positive swabs pre-dose two in negative baseline participants was 14 in the vaccine group and 38 in the placebo group, suggesting that some asymptomatic infections may be prevented with just the first dose.

If you have any questions or concerns, please call the clinic.