Allergic Reactions to COVID Vaccines Are Rare, Resolved on Site: CDC

Cases of anaphylactic shock caused by COVID-19 vaccines are very rare, based on numbers from the first week and a half of vaccinations in the United States, federal public health officials said Wednesday.

There have been 21 cases of anaphylaxis out of nearly 1.9 million doses of the Pfizer-BioNTech vaccine administered in the very first days of the national COVID-19 vaccination program, said Dr. Nancy Messonnier, director of the National Center for Immunization and Respiratory Diseases at the U.S. Centers for Disease Control and Prevention.

“We’re in the setting of 2,000 COVID deaths per day. If you make that comparison, I think it’s still a good value proposition for someone to get vaccinated,” Messonnier said. “Their risk from COVID and poor outcomes from COVID is still more than their risk of a severe outcome from the vaccine.”

The average rate is 11.1 anaphylaxis cases per one million doses administered, which is higher than the rate of anaphylaxis for flu vaccine of 1.3 per one million doses administered, Messonnier noted.

“I guess you could mathematically say that’s 10 times the amount, but I think that misses the point,” Messonnier said. “This is exceedingly rare, and I think that is still the message that the public should be getting from this.”

Anaphylaxis occurs rapidly following COVID-19 vaccination, with symptom onset within 13 minutes of receiving the shot on average, Messonnier said. Seven out of 10 cases occurred within 15 minutes of vaccination.

Of the 21 patients, 17 “had a documented history of allergies or allergic reactions, including to drugs or medical products, foods and insect stings,” Messonnier said.

The cases occurred with doses from multiple vaccine lots, which means a single batch isn’t to blame.

“Anyone who has an immediate or allergic reaction to the first dose of Pfizer or Moderna’s vaccine should not receive the second dose,” Messonnier said. “Anyone with a history of an immediate allergic reaction to a vaccine or injectable therapy, and people with a history of anaphylaxis due to any cause should be observed for 30 minutes after vaccination.”

In 19 of the 21 cases, patients were given an epinephrine injection — standard care for anaphylactic shock. No one died as a result of their severe allergic reaction, the CDC said.

“We know how to treat anaphylaxis, and we’ve put provisions in place to ensure that, at immunization sites, the folks administering the vaccine are ready to treat anaphylaxis,” Messonnier said.

The CDC data was published online Jan. 6 in the agency’s Morbidity and Mortality Weekly Report.

In a separate publication, Dr. Aleena Banerji, head of the allergy and clinical immunology unit at Massachusetts General Hospital in Boston, and her colleagues agreed that the two COVID-19 vaccines approved in the United States are safe and effective, even for people with food or medication allergies.

The research team offers some advice in the Dec. 31 Journal of Allergy and Clinical Immunology: In Practice, so that people with different allergy histories can safely receive their first COVID-19 vaccine.

“As allergists, we want to encourage vaccination by reassuring the public that both [Food and Drug Administration]-approved COVID-19 vaccines are safe,” Banerji said in a hospital news release. “Our guidelines are built upon the recommendations of U.S. regulatory agencies and provide clear steps to the medical community on how to safely administer both doses of the vaccine in individuals with allergic histories.”

People with a history of severe allergy (anaphylaxis) to a drug or vaccine should speak with their allergists before being vaccinated, Banerji and her group said. However, those with severe allergies to foods, oral drugs, latex or venom can still be safely vaccinated, they noted.

More information

The U.S. Centers for Disease Control and Prevention has more about COVID-19 vaccines.

SOURCES: Nancy Messonnier, MD, director, National Center for Immunization and Respiratory Diseases, U.S. Centers for Disease Control and Prevention; Massachusetts General Hospital, news release, Dec. 31, 2020; Morbidity and Mortality Weekly Report, Jan. 6, 2021, online