Study to evaluate how people with immune system deficiencies respond to COVID-19 vaccination A study assessing how people with immune system deficiencies or dysregulations respond to COVID-19 vaccination has begun enrolling participants at the National Institutes of Health Clinical Center in Bethesda, Maryland. The single-site study is led by researchers from the National Institute of Allergy and Infectious Diseases (NIAID) and aims to enroll 500 people, 400 with primary or secondary immune system disorders and 100 without such conditions. "Through large Phase 3 trials, several experimental COVID-19 vaccines were shown to be safe and effective and three are now authorized by the U.S. Food and Drug Administration for emergency use in the United States," said NIAID Director Anthony S. Fauci M.D.