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Experts say COVID-19 vaccines can be safely administered to most people who are designated as highly allergic. Me789 Studio/Getty Images
  • Serious allergic reactions to COVID-19 vaccines are rare, according to a new study.
  • Experts say special precautions should be taken to safely vaccinate people at high risk of allergic reaction.
  • They add that people with a history of allergic reactions should consult their doctors about getting vaccinated against COVID-19.

Allergic reactions to COVID-19 vaccines are rare, according to new research published in JAMA Network Open.

This large, prospective study involved the Pfizer-BioNTech COVID-19 vaccine, one of three COVID-19 vaccines currently in use in the United States.

“We assume that these lessons will be generalizable to the Moderna and other mRNA vaccines with similar excipients and constructs,” Dr. Elizabeth J. Phillips, a professor in the department of medicine at Vanderbilt University Medical Center in Tennessee, said in an editorial that accompanied the study.

The researchers gathered data from December 27, 2020 to February 22, 2021 at Sheba Medical Center in Israel.

More than 8,000 people with allergies went through risk assessment using an algorithm that included a detailed questionnaire.

Slightly more than 400 participants were defined as “highly allergic.” Of those, 71 percent were women.

This group received the vaccine under medical supervision. Following the first dose:

  • Almost 98 percent of participants had no allergic reaction.
  • Slightly more than 1 percent of participants developed a mild allergic response, such as skin eruptions, flushing, swelling of the tongue or uvula, or cough.
  • Less than 1 percent of participants had an anaphylactic reaction, a potentially life-threatening condition.

Anaphylactic reactions appeared within 10 to 20 minutes after vaccination. Treatment included adrenaline, antihistamines, and an inhaled bronchodilator. Symptoms resolved within 2 to 6 hours. None of the participants needed hospitalization.

The participants who had an anaphylactic reaction didn’t get a second dose in this study period.

Slightly more than half the group got their second dose during the study period. After the second dose, 98 percent of participants had no allergic reaction, while almost 2 percent experienced a mild reaction.

Study authors concluded that the rate of allergic reactions to the Pfizer-BioNTech COVID-19 vaccine is higher than for other commonly used vaccines, especially in people with a history of allergic reactions.

However, most people with a history of allergies can be safely immunized with use of an algorithm that includes risk assessment and medical supervision for those who are highly allergic.

The researchers acknowledge the need for more studies to define the exact risk factors for anaphylaxis among highly allergic people.

One of the researchers, Dr. Gili Regev-Yochay, disclosed receiving personal fees from Teva and grants from Pfizer outside the submitted work.

Dr. Jan K. Carney is the associate dean for public health and health policy and a professor of medicine at Larner College of Medicine at the University of Vermont.

Carney told Healthline the research was well-conducted.

“The study helps us identify (screen) patients for an especially high risk of severe allergy against COVID-19 and determine safe and practical vaccination approaches against this deadly virus,” she said.

Carney said it’s important to note that not all reported allergies are the same.

“The priority is to identify severe and potentially life-threatening allergy risks, especially anaphylactic reactions,” she said.

“I agree with the [Centers for Disease Control and Prevention (CDC)] that the safest route is to check with your primary healthcare provider about your health and allergy history,” Carney said.

If you had an allergic reaction to a first dose, Carney recommends speaking with your primary care doctor about whether you can safely get the second dose or if you should consider another type of vaccine.

Dr. Flavia Cecilia Lega Hoyte is an allergist and immunologist in the Division of Allergy and Clinical Immunology at National Jewish Health in Colorado.

Hoyte told Healthline that the Pfizer-BioNTech and Moderna COVID-19 mRNA vaccines are new and don’t overlap with other vaccines, such as those for flu or shingles.

“A previous allergic reaction is not a contraindication for COVID-19 vaccines,” she explained.

“Even in patients who have symptoms, it’s often not a true allergic reaction. But anyone who feels they’re in that group should talk to an allergist,” Hoyte said.

National Jewish Health is one of 29 locations recruiting participants for a clinical trial to assess allergic reactions to the Pfizer-BioNTech and Moderna vaccines. Two-thirds of the participants will be women, because they make up the majority of anaphylaxis cases due to COVID-19 vaccines.

Hoyte advised that high-risk people can be monitored longer and with medicines on hand.

“If they have a severe reaction, such as anaphylaxis, we can treat them quickly and effectively,” she said. “We can also premedicate with an antihistamine about an hour before, which can the edge off mild reactions.”

Another option is to split the dose for slower administration.

“We might do a portion of the dose and give the rest a half hour or an hour later. It’s what we’ve done for years with other vaccines to minimize risk without sacrificing the protection of a vaccine,” Hoyte said.

The main point, she added, is to get your COVID-19 vaccine.

The specific type of allergy and medical history is also important.

“Most people can be safely vaccinated — the vast majority in usual vaccination clinics or office settings,” Carney said. “However, we must also identify people with histories of severe allergy type, especially anaphylaxis, and determine whether and how these individuals can be safely vaccinated.”

Carney stressed that vaccines are the best protection against a serious and sometimes fatal virus.

“My advice is for people with allergy histories to discuss their medical history with their primary care professional to determine any potential risk for severe allergic reaction and to advise them as to the best course of action for their health during the pandemic,” Carney said.