Detecting Disease Transmission: Comparing SARS-CoV-2 Cases in a County Jail and the Surrounding Community

Early detection of infectious disease transmission is an important public health tool. We sought to evaluate how positive severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) cases, identified within 14 days of admission to a jail setting, are linked to local county incidence. Data were extracted from the electronic health record and publicly accessible websites. We compared positive cases of SARS-CoV-2 identified in the Santa Clara County (SCC) jail within 14 days of admission (250 cases) with positive cases reported in SCC (141,841 cases) between March 15, 2020, and October 2, 2021. There was a strong, positive correlation between cases of SARS-CoV-2 identified within 14 days of jail admission and SCC cases the following week (r = .785). Our findings show that admission SARS-CoV-2 testing data from jails may be useful for detecting disease transmission in the surrounding community.