Concerns over Delta variant rise as more unvaccinated people contract COVID Concerns over Delta variant rise as more unvaccinated people contract COVID DC Health reported four deaths and 200 confirmed ‘break-through’ cases as concerns rise over the COVID-19 Delta variant. WASHINGTON (FOX 5 DC) - Starting Thursday, D.C.’s Department of Health will now require lab partners to do more sequencing of positive COVID-19 samples as concerns rise around the growing Delta variant. "According to the CDC, approximately 45 percent of new cases in HHS Region 3, which includes DC, are due to the Delta variant," a press release from Mayor Muriel Bowser's officer read.