State-Mandated Mitigation Measures Reduce COVID-19 Impacts, CDC Finds

State-mandated mitigation measures combined with public health interventions contributed to a significant reduction in COVID-19 incidence, hospitalizations, and mortality in Delaware from late April to June of this year, according to a new report from CDC. The report examines mitigation measures such as stay-at-home orders and public mask mandates and interventions like case investigations with contact tracing.

CDC reports that in the weeks and months following Delaware’s first reported COVID-19 case on March 11, 2020, the state commenced investigation of all known cases, issued statewide stay-at-home orders and a public mask mandate, and began contact tracing efforts. COVID-19 incidence, hospitalization, and mortality rates initially increased after Delaware’s stay-at-home order was issued on March 24, peaking during the week of April 13. All three metrics then declined by 18 percent, 20 percent, and 13 percent, respectively, until the week of April 20, when rates began to increase slightly. Rates declined again during the week that the state’s mask mandate went into effect on April 28. From late April through June, incidence, hospitalization, and mortality rates fell dramatically. By June, COVID-19 incidence had declined by 82 percent, hospitalizations by 88 percent, and mortality rates by 100 percent. CDC notes that contact tracing began on May 12, joining existing public health interventions such as case investigations, the stay-at-home order, and the mask mandate.

“A stay-at-home order and case investigations instituted weeks before the peak in COVID-19 cases (week of April 13) in Delaware likely contributed to the subsequent decline observed in COVID-19 incidence and associated hospitalization and deaths,” the report states. “As expected, the impact on incidence was not immediate but occurred weeks after measures were implemented, as new cases represented exposure that occurred during previous weeks.”

CDC notes that the early detection, self-isolation, and investigation of COVID-19 cases and the self-quarantine of patients’ close contacts can also reduce community spread of COVID-19. But the report identifies several barriers to successful contact tracing and case investigation. Between March 11 and June 25, 6,527 patients with laboratory-confirmed COVID-19 (representing about two-thirds of all confirmed cases in the state during that time) were interviewed by the Delaware Division of Public Health (DPH). Eighty-three percent of interviewed patients refused to disclose or could not recall their contacts. DPH could not reach many of the contacts that were identified. CDC suggests that these issues could be reduced by earlier initiation of COVID-19 case investigation and improved daily and weekly data monitoring.