With tens of thousands of new coronavirus cases daily in the U.S., states are launching digital apps that alert people if they have been exposed to someone who tested positive for the virus. Virginia recently rolled out a COVID exposure app that became instantly popular with residents. Health officials are trying to determine whether such apps will work to help slow virus transmission. VOA’s Julie Taboh has more.Producers: Julie Taboh, Adam Greenbaum. Videographers: Adam Greenbaum, VPM, Skype, VDH.