The Centers for Disease Control and Prevention on Sunday said people who have experienced severe reactions to prior vaccines or injectable drugs can still get the Pfizer/BioNTech vaccine for Covid-19, but should discuss the risks with their doctors and be monitored for 30 minutes afterward.
The guidance is a shift from a prior proposal laid out Saturday that would have recommended against vaccination for that group of people. During a webinar with physicians, CDC officials said patients with a history of severe reactions should take precautions because of two documented cases of anaphylaxis in British health care workers who received the Pfizer/BioNTech vaccine.
“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, a medical officer with the CDC’s National Center for Immunization and Respiratory Diseases.
Mbaeyi said people should discuss a prior allergic reaction with their doctors to help assess whether it was truly caused by an injectable medicine and constituted a severe reaction. The specific reaction providers are trying to avoid is anaphylaxis, which is life-threatening and causes symptoms such as dizziness, difficulty breathing, wheezing, and a fast heart rate.
Mbaeyi said people with other types of allergies — to food, latex, pollen or other substances — do not have to take special precautions and are recommended to receive the Pfizer/BioNTech vaccine.
The guidance differs from instructions issued by British regulators, who are recommending against vaccination for people who have experienced anaphylaxis due to allergies to food or medicine. The cases of anaphylaxis in that country are still under investigation, as the cause remains unknown.
In the U.S., regulators are only recommending against vaccination for people with an allergy to a specific component for Pfizer/BioNTech vaccine. The recommendation is contained in a fact sheet issued by the Food and Drug Administration, which granted an emergency use authorization to the Pfizer/BioNTech product late Friday.
Severe allergic reactions to vaccines are extremely rare and were also rare during the Pfizer/BioNTech trial, which excluded people with a history of anaphylaxis. The FDA has released data indicating .63% of participants who received the vaccine experienced serious adverse reactions, compared to .51% of people who received a placebo.
During the CDC call on Sunday, officials said they had received multiple questions about allergic reactions to the vaccine and the components within it. Amanda Cohn, an official with the CDC’s Covid-19 vaccine planning unit, said the vaccine consists of messenger RNA and four lipid nanoparticles and that there are no preservatives or other ingredients in the vaccine.
She said people could be allergic to a part of the lipid nanoparticle known as polyethylene glycol, or PEG, which is a component in other injectable medicines. “That is partially the reason for the extra precautions for persons who have (had reactions) to other injectables, Cohn said. “We are being abundantly cautious about this question related to allergic reactions. We don’t want people who have mild allergic reactions to be concerned about getting vaccinated.”
The FDA has said it will monitor any allergic reactions closely as the vaccines roll out and may need to modify its guidance going forward. CDC officials made the same promise on Sunday as the first doses were shipped across the U.S.
“We will learn a lot more as we follow the use of this vaccine very carefully,” Cohn said. “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.”