CDC Says Pfizer, BioNTech COVID-19 Vaccine is Safe For Patients With History of Severe Allergic Reactions


Among a subset of participants in the COVID-19 vaccine clinical trials, 0.63% of individuals in the vaccinated group had hypersensitivity-related adverse events that may represent allergic reactions.

In a new release, the CDC said individuals with a history of severe allergic reactions can still receive the coronavirus disease 2019 (COVID-19) vaccine from Pfizer and BioNTech, although they should discuss the risks with their physician and should be monitored for 30 minutes after receiving the injection.1

The vaccine series from Pfizer and BioNTech, which received an emergency use authorization from the FDA on December 11, consists of 2 doses administered 3 weeks apart within a 4-day grace period. However, if the second dose is administered earlier than 17 days after the first dose, it does not need to be repeated, according to the CDC guidance.1 It is not interchangeable with other COVID-19 vaccine products.1

The report said providers should counsel vaccine recipients about expected local and systemic post-vaccination symptoms. Local symptoms may include pain, swelling, and erythema at the injection site, whereas systemic symptoms may include fever, fatigue, headache, chills, myalgia, and arthralgia. Clinical trial data demonstrated that 85% of vaccinated persons developed at least 1 local injection site symptom and 77% developed at least 1 systemic symptom following vaccination.1

Among a subset of participants in the clinical trials, the CDC said 0.63% of individuals in the vaccinated group had hypersensitivity-related adverse events that may represent allergic reactions.1 Although not observed in the clinical trials, the report said anaphylaxis has been reported during mass vaccinations outside of clinical trials. A history of severe allergic reaction to any component in the vaccine is a contraindication, and antipyretic or analgesic medication can be taken for the treatment of post-vaccination symptoms.1

“People that do report those types of anaphylactic reactions to other vaccines or injectables—they can still get the vaccine, but they should be counseled about the unknown risks of developing a severe allergic reaction and balance these risks against the benefit of vaccination,” said Sarah Mbaeyi, MD, MPH, a medical officer with the CDC’s National Center for Immunization and Respiratory Diseases, according to reporting from PBS.2

The report also discussed considerations for other patient populations, including those with immunocompromising illnesses or those who are pregnant.

For individuals with evidence of a prior COVID-19 infection, the CDC said data from phase 2 and 3 clinical trials suggest that the vaccine is safe and likely efficacious, and should be offered regardless of their history of symptomatic or asymptomatic infection. Vaccination should be deferred for individuals with a known current diagnosis of COVID-19 until they have recovered and criteria have been met for them to discontinue isolation.1

There are currently no available data for the use of the vaccine as post-exposure prophylaxis. Because protection from the virus takes 1 to 2 weeks following the second dose of the vaccine and the median incubation period is 4 to 5 days, the CDC said current evidence suggests that vaccination following a known exposure to COVID-19 is unlikely to be an effective strategy for preventing disease.1

The vaccine may be administered to individuals with underlying medical conditions who have no contraindications, and phase 2 and 3 clinical trials have demonstrated similar safety and efficacy profiles in this patient population, according to the CDC. Individuals with HIV infection or other immunocompromising conditions may be at increased risk for severe COVID-19, and data are not currently available to establish safety and efficacy in these groups, though the CDC said they can still receive the vaccine if they have no contraindications.1

Similarly, observational data have suggested that pregnant people with COVID-19 may be at an increased risk of severe illness and adverse pregnancy outcomes, although the absolute risk is low according to the CDC release. There are currently no available data on the safety of COVID-19 vaccines in this patient population, although current knowledge suggests that mRNA vaccines are unlikely to pose a risk for pregnant patients. If pregnant individuals are part of a group who is recommended to receive a COVID-19 vaccine, the CDC said they can choose to be vaccinated.1

“We will learn a lot more as we follow the use of this vaccine very carefully,” said Amanda Cohn, MD, of the CDC’s COVID-19 vaccine planning unit, in reporting by PBS. “We know that these vaccines have the potential to end this pandemic and we know that it is critical for health care providers to have confidence that these vaccines are very safe.”2


  • Centers for Disease Control and Prevention: Interim Clinical Considerations for Use of Pfizer-BioNTech COVID-19 Vaccine. Released December 14, 2020. Accessed December 15, 2020.
  • Ross C. CDC says people with history of severe allergic reactions can get COVID-19 vaccine. PBS News Hour; December 14, 2020. Accessed December 15, 2020.

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