JACKSONVILLE, Fla. A clinical research group based in Jacksonville is doing its part to help scientists develop a reliable COVID-19 vaccine. The Jacksonville Center for Clinical Research was one of only a handful of private research entities awarded COVID-19 vaccine trials. At the center, Dr. Michael Koren and his team are working on two different COVID-19 vaccine studies -- one for pharmaceutical company Pfizer and the other for biotechnology company Moderna. Phase three of Koren and his teams research requires at least 500 volunteers from Jacksonville. They are being exposed to COVID-19 day to day, Koren said.