Delta cases IDâd in Delta County Two cases of the Delta COVID-19 variant have been identified in Delta County weeks after the new variant arrived in Mesa County. The Delta County Health Department on Thursday confirmed that, through sequencing of test samples, the Delta variant, which was first identified in India and has no relation to the county, was identified in two Delta County COVID-19 cases. The Delta variant has been identified in 30 Colorado counties, according to a press release from Delta County Public Health. Officials warn itâs considered significantly more transmissible than the first detected Alpha variant of COVID-19, and is associated with increased severity. To date, 75% of all COVID-19 cases in Colorado are derived from the Delta variant.