Twenty-nine recipients of COVID-19 vaccines in the United States have had severe allergic reactions after receiving the injection, health officials said Wednesday.
The Centers for Disease Control and Prevention said anaphylaxis, a potentially life-threatening allergic reaction, occurred in recipients of both the Moderna and Pfizer vaccines, although officials insisted it was a “rare outcome” and no deaths were reported.
“As you can imagine, enormous efforts are being made to understand what may be the cause of these allergic reactions,” said Dr. Nancy Messonnier, director of the agency’s National Center for Immunization and Respiratory Diseases, to reporters.
Messonnier said they are still collecting information on all cases of anaphylaxis – especially with the Moderna vaccine, as it is less responsible for the 4.8 million doses administered to date.
The agency revealed in a report on Wednesday that there were 21 cases of anaphylaxis in the 1.9 million people who received the first dose of the Pfizer vaccine.
Seventeen of the 21 people had a documented history of allergies or allergic reactions, seven of whom had previously had anaphylaxis, Messonnier said.
But the rate is higher than in people who got the flu shot.
Flu vaccines cause anaphylaxis in an estimated 1.3 people per 1 million recipients, while about 11.1 Pfizer recipients in every million had the response, the CDC estimates.
“You could mathematically say that’s 10 times the amount, but I think I’m wrong because it’s still extremely rare,” Messonnier said.
“We would all hope that any vaccine would have no side effects, but even in 11 cases for 1 million doses administered, it is a very safe vaccine.”
She added that the risk of contracting COVID-19 or experiencing a poor outcome from the virus is still higher.
“Fortunately, we know how to treat anaphylaxis and have provisioned for immunization sites,” Messonnier said.
Anyone who has an allergic reaction to the first COVID-19 vaccine dose is not recommended to get the second shot of the two-dose regimen, Messonnier said.
The agency urges anyone with a history of allergies to see their health care provider to determine if they are getting the vaccine.
“There is a difference between someone who had a mild allergic reaction in childhood and someone who had a severe allergic relationship last week,” Messonnier said.
“It will be important to have a physician assist in assessing judgment rather than having set rules.”