Researchers are looking for participants in a coronavirus vaccine trial that starts soon in San Antonio. The trial will be conducted at Clinical Trials of Texas in the Medical Center. Screening for possible participants started on Thursday. Test subjects must be at least 18 and not have had the virus before. Any underlying health conditions must be under control. First responders and other frontline workers with high risk of exposure to the virus are encouraged to apply. People who participate will not catch the virus from the vaccine. The worldwide trial will involve 30-thousand subjects, and it starts on July 27th.