CDC: Severe allergic reaction to vax is rare

Only 21 people out of the first 1.9 million recipients of the Pfizer coronavirus vaccine in the U.S. suffered a severe allergic reaction, the CDC reported Wednesday.

An anaphylaxis case after getting the Pfizer vax appears to be an extremely rare event, based on early safety monitoring, the Centers for Disease Control and Prevention said.

The majority of these severe allergic reactions (71%) happened within 15 minutes of receiving the shot.

Of the 21 anaphylaxis cases, 17 of the people have a documented history of allergies or allergic reactions, including to drugs or medical products, foods, and insect stings. Seven of the people had experienced an episode of anaphylaxis in the past, including one after getting a rabies vaccine and another after receiving an influenza (H1N1) vaccine.

Four of the patients were hospitalized, and 17 of the patients were treated in an emergency department. No deaths from anaphylaxis were reported after receiving the Pfizer COVID-19 vaccine.

The allergic reaction data from the CDC comes after officials recently noted that the reactions could be tied to a chemical called polyethylene glycol, which is found in both the Pfizer and Moderna vaccines.

A Boston oncology doctor with a shellfish allergy experienced a severe allergic reaction after he received Moderna’s coronavirus vaccine at the end of December.

Because the FDA emergency use authorization for the Moderna COVID-19 vaccine was received one week later than the Pfizer vaccine, the CDC report on Wednesday focused on the Pfizer vaccine. An assessment of adverse events reported after receiving the Moderna COVID-19 vaccine will be forthcoming, the CDC said.