An analysis today by the Centers for Disease Control and Prevention (CDC) of COVID-19 case investigation and contact tracing data from 56 US health departments shows that heavy investigator caseloads and an unengaged public may hinder the ability to locate and quarantine contacts in a timely manner.The study, published in Morbidity and Mortality Weekly Report, used health department reports from Jun 25 to Jul 24, 2020, to determine the effectiveness of case investigation and contact tracing in mitigating the transmission of SARS-CoV-2, the virus that causes COVID-19, through rapid identification, testing, and quarantine of contacts.Sixty-two of 64 health departments funded by the Epidemiology and Laboratory Capacity for Prevention and