Modern COVID-19 vaccine rarely causes severe allergic reactions, according to new data released by the Centers for Disease Control and Prevention (CDC).
Between December 21 and January 10, more than 4.04 million people received the COVID-19 vaccine from Moderna, but only 10 developed a severe and life-threatening allergic reaction called anaphylaxis. According to the CDC, it is estimated that there are about 2.5 cases of anaphylaxis for every million people vaccinated. Weekly morbidity and mortality report.
It is not yet clear what causes severe allergies, but nine out of 10 of these cases occurred in patients with previously known allergies (five previously had anaphylaxis). Most had
allergies to various medications such as penicillin, but one had environmental and food allergies and another had no previously known allergies, according to the report.
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Nine out of 10 patients developed symptoms (such as vomiting, nausea, wheezing, swelling of the tongue, and rash) within 13 minutes of getting the vaccine and one developed symptoms within 45 minutes.
All 10 patients were treated with epinephrine, a hormone also known as adrenaline, which is the key ingredient in EpiPens and similar autoinjectors; four were treated in an emergency department and six were hospitalized, and four required intubation. But all 10 patients recovered, according to the report.
“According to this early follow-up, anaphylaxis after receiving the Modern COVID-19 vaccine appears to be a rare occurrence,” the authors wrote in the report. But because there is still no widespread data on COVID-19 vaccines, it is difficult to compare the risk of anaphylaxis with non-COVID-19 vaccines, they wrote. In a previous one Weekly morbidity and mortality report, published on January 15, the researchers estimated that the Pfizer-BioNTech vaccine causes anaphylaxis in approximately 11.1 cases per million doses (0.001% probability); this estimate was based on early data.
However, both anaphylaxis associated with Pfizer and Moderna COVID-19 vaccines appear to be above the average number of anaphylaxis cases found in previous vaccines. In 2015, researchers estimated that the chance of developing a severe allergic reaction to a vaccine is about 1.31 in 1 million, according to a study published in 2015 in the Journal of Allergy Clinical Immunology. “True allergic reactions to vaccines are very rare,” said Dr. Purvi Parikh, an allergist and immunologist at NYU Langone Health. he had previously told Live Science. “Statistically, you’re more likely to be affected by lightning that has a true anaphylactic reaction to a vaccine.” While cases are extremely rare, and should not deter people from the vaccine, experts are working to identify what could cause allergies.
People who have had an allergic reaction to the first dose of the vaccine should not receive the second dose, the authors wrote. Vaccination centers should have all the necessary supplies and trained staff to treat anaphylaxis, they wrote. The CDC also recommends that people receiving COVID-19 vaccines should also be monitored for about 15 minutes or 30 minutes if they have a history of allergies or anaphylaxis.
Originally published in Live Science.