TALLAHASSEE, Fla. University of Florida Health announced Tuesday it enrolled two patients in a national clinical trial about convalescent blood plasma and whether it can reduce the effects of COVID-19. UF Health is one of 50 medical centers nationwide participating in the clinical trial, which is expected to enroll 600 patients. Enrolled patients must have a mild form of COVID-19 but be at risk of developing more severe cases because of immunity issues, their ages, lung disease or diabetes, Lisa H. Merck, a physician who is vice chair of research in the UF College of Medicines Department of Emergency Medicine and site principal investigator, said in a prepared statement. Researchers are interested in how patients respond in the first two weeks of their illness but will track patients for a month. It is a blind clinical trial, meaning patients wont know whether they have been given convalescent blood plasma or placebos.