Severe Allergic Reactions to COVID-19 Vaccines Are Rare: CDC Report

in Food Allergy, Food Allergy News
Published: January 23, 2021
Covid-19 Vaccine vials
Photo: Getty Images

The U.S. Centers for Disease Control and Prevention has provided an updated – and largely reassuring – picture of allergic reactions after the COVID-19 mRNA vaccines.

As the number of shots given quickly grows, the CDC says that 15 adults have experienced anaphylaxis after receiving the Moderna vaccine as of Jan. 19. Also as of that date, a CDC spokesperson said there have been 45 cases of anaphylaxis after the Pfizer-BioNTech vaccine. 

That translates to a rate of 2.1 cases of anaphylaxis for every 1 million people receiving the Moderna vaccine and 6.2 cases for every 1 million receiving the Pfizer-BioNTech vaccine.    

It has long been known that any type of vaccine carries a small risk of an anaphylactic reaction. As of now, the rate of reactions to the two mRNA coronavirus vaccines approved for emergency use is “comparable” to other vaccines, CDC spokesperson Jasmine Reed said in a statement to Allergic Living.

“Early monitoring of both the Moderna and the Pfizer-BioNTech COVID-19 vaccines indicate that anaphylaxis following vaccination is a rare event, and although anaphylaxis is serious, it occurs shortly after vaccination (usually within minutes), is readily diagnosed, and effective treatments are available,” said Reed.

With millions more set to receive a COVID-19 vaccine in the coming weeks, the rate of anaphylactic reactions may change, she noted. Earlier data, from a CDC report issued Jan. 6, estimated the rate of anaphylactic reactions to the first dose of the Pfizer vaccine at 11.1 cases per million. So the newer data revises that downward.

mRNA Reactions Higher Among Women

The CDC on Jan. 22 released its second report on allergic and anaphylactic reactions to the mRNA vaccines. This new report focuses on the Moderna vaccine, which began its rollout in the U.S. a week later than the Pfizer vaccine.

The report data, gathered between Dec. 21 and Jan. 10, confirm 10 cases of anaphylaxis in this three-week period among 4 million people who received a first dose of the Moderna vaccine. Of the 10 people who had anaphylactic reactions, nine had a history of allergies or allergic reactions. The most common symptoms were a range of rash, nausea, wheezing and swelling of the tongue.

Six of the anaphylaxis patients had known allergies to drugs, two were allergic to intravenous contrast dye used for imaging tests such as MRIs, and one to unspecified foods. Five had a history of anaphylaxis.

All 10 reactions occurred in women. Although more women than men have thus far received the vaccine, there is nonetheless a “strong female predominance” of anaphylaxis to the vaccine, according to the CDC.

As is common with anaphylaxis, allergic reactions came on quickly, with symptoms beginning an average of 7.5 minutes after receiving the Moderna vaccine. All received epinephrine, six were admitted to hospital, and four required intubation to assist with breathing. The report says there were no deaths.

Other Types of Reactions

Health providers are being encouraged to report any adverse mRNA reactions, and there were about 100 Moderna vaccine reactions determined not to be anaphylaxis. The CDC data show 43 were considered non-anaphylactic allergic reactions and again, most who reacted were women.

Another 47 were other types of reactions, mostly vasovagal responses such as fainting or the feeling of fainting, or anxiety-related symptoms.

Anaphylaxis is a severe, life-threatening allergic reaction that occurs rarely after vaccines, including childhood vaccines and flu shots. Previous estimates put the rate of anaphylaxis after any vaccine at about 1.31 in 1 million in adults and children.

Reports of severe allergic reactions to the mRNA vaccines have stirred vigorous debate among allergists and immunologists as to the possible cause, but as yet, no cause or causes have been determined.

Provider Precautions with mRNA Vaccines

The CDC recommends that COVID-19 vaccine sites have epinephrine and trained staff on hand to ensure prompt treatment for anaphylaxis. Everyone who receives an mRNA vaccine should be observed for 15 minutes afterward, while people with a history of anaphylaxis should be monitored for 30 minutes.

Allergists urge people with food allergies, environmental allergies and asthma to get the coronavirus vaccine as soon as they are eligible. The CDC also says that it’s safe for people with a history of allergies or anaphylaxis to get the vaccine, with the exception of those who have had an allergic reaction to a component in the vaccine.

“Patients experiencing anaphylaxis after vaccination do well and recover. Unfortunately, COVID-19 cases, hospitalizations, and deaths continue to increase. When combined with other protective measures, vaccines are one of the best tools we have to fight the pandemic,” the CDC said.

Anyone who has an immediate reaction after the first dose of an mRNA COVID-19 vaccine should not receive the second dose.  

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