The U.S. National Institutes of Health (NIH) announced Wednesday a clinical trial was under way to determine the risk of allergic reactions to the COVID-19 vaccines manufactured by Moderna and Pfizer. A press release from the NIH says the trial will determine whether people are highly allergic to the vaccine or have a disorder that puts them at an increased risk for an immediate, systemic allergic reaction to the vaccine. While the vaccines are considered safe, several rare allergic reaction incidents — including serious episodes, known as anaphylaxis — have been reported in the U.S. after Pfizer-BioNTech and Moderna shots were given. The trial will also examine the biological mechanism behind allergic reactions in the body and whether a certain genetic pattern or other factors can be used to predict high-risk recipients. FILE – A patient receives a shot of the Moderna COVID-19 vaccine at a CVS Pharmacy branch in Los Angeles, March 1, 2021.”The information gathered during this trial will help doctors advise people who are highly allergic or have a mast cell disorder about the risks and benefits of receiving these two vaccines. However, for most people, the benefits of COVID-19 vaccination far outweigh the risks,” Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases (NIAID), part of the NIH, said in the statement. NIH says a mast cell disorder is a disease caused by a type of white blood cell called a mast cell that is abnormal, overly active, or both, predisposing a person to life-threatening reactions. The Phase 2 trial, called Systemic Allergic Reactions to SARS-CoV-2 Vaccination, is sponsored and funded by NIAID. The vaccines used in the trial are provided by the program led by the U.S. Department of Health and Human Services and the U.S. Department of Defense that develops COVID-19 vaccines and therapeutics. The study will include 3,400 adults ages 18 to 69 at up to 35 academic allergy research centers nationwide. 
 
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