1 of 3 | Allergic reactions to the COVID-19 vaccines are rare, even among those with a history of allergies, a new study has found. File photo by Debbie Hill/UPI | License Photo
Aug. 31 (UPI) -- Allergic reactions to the COVID-19 vaccine are rare, even among recipients with a history of complications in response to inoculations, medications and other irritants, a study published Tuesday by JAMA Network Open found.
Still, special precautions should be taken to safely vaccinate those at high risk for allergic reactions, the researchers said.
Among more than 400 participants described as "highly allergic," 98% had "no immediate" reaction following receipt of the Pfizer-BioNTech vaccine, the data showed.
Six, or fewer than 2%, of the study participants had "minor allergic responses," while three, or fewer than 1%, experienced anaphylaxis.
The rate of allergic reactions, particularly anaphylactic reactions, to the Pfizer-BioNTech vaccine are higher than for other commonly used vaccines, "particularly for patients with a history of allergic reactions," according to the researchers.
However, even those with a history of allergic reactions to vaccines should still get the shot, under supervised conditions, given the deadly nature of the virus, they said.
"Allergies are very common -- up to 40% in the general population, and many avoid immunization due to these concerns and particularly as the COVID-19 vaccine was found to be relative to other vaccines more allergenic," study co-author Dr. Nancy Agmon-Levin told UPI in an email.
"In our study, most allergic patients could be immunized [with an] algorithm for screening that can be implemented by physicians and nurses in any medical setting," said Agmon-Levin, an immunologist at Sheba Medical Center in Tel-Hashomer, Israel.
The risk of severe allergic reactions, including anaphylaxis, with the currently available COVID-19 vaccines from Johnson & Johnson, Moderna and Pfizer-BioNTech is "very low," according to research published earlier this year.
In data released early in the vaccine rollout, just 29 of 4.8 million vaccine recipients developed a severe allergic reaction to the shots, the Centers for Disease Control and Prevention reported.
In all cases, those affected experienced anaphylaxis, which the Mayo Clinic describes as a "potentially life-threatening allergic reaction" that occurs within seconds or minutes of exposure and in which the immune system releases a flood of chemicals, causing the body to go into shock.
For this study, the Israeli researchers administered the Pfizer-BioNTech vaccine, the predominant one used in the country, to 429 adults with a history of allergies.
Among the study participants, 68, or 16%, had food allergies and 141, or 33%, had multiple drug allergies.
In addition, because of their allergies, 95, or 22%, of the participants routinely carried an adrenaline syringe to use as an emergency treatment for anaphylaxis.
To ensure that the COVID-19 vaccine was safely administered to these participants, the researchers established a protocol that identified patients at risk and educated them on the potential hazards associated with inoculation.
The approach required a two-hour observation period following receipt of both the first and second doses of the vaccine.
During the two-hour observation period following the first dose, nine women experienced allergic reactions, with mild, immediate allergic reactions -- such as rash, swelling of the tongue or uvula, or cough -- occurring in six.
All of these reactions resolved after treatment with antihistamines, the researchers said.
The three patients who developed anaphylaxis did so within 10 to 20 minutes of getting their shots, and were treated with adrenaline, antihistamines and an inhaled bronchodilator, or a "rescue inhaler," to relax the muscles around the airway, which can tighten during the reaction.
None of the participants required hospital care and all recovered fully with two to six hours.
Among the 218 participants who received the second dose of the vaccine, four developed mild allergic reactions that resolved during the two-hour observation period, the data showed.
Three of the four also experienced reactions following the first dose, according to the researchers.
"We enabled immunization of most patients with allergies by using a simple algorithm that included a referral center, a risk assessment questionnaire and a safe environment for immunization of highly allergic patients with observation after immunization," the researchers wrote.
"This algorithm can be implemented in any medical setting to allow immunization for all, they said.