Community Transmission of SARS-CoV-2 at Two Family Gatherings - Chicago, Illinois, February-March 2020.

SARS-CoV-2, the virus that causes coronavirus disease 2019 (COVID-19), has spread rapidly around the world since it was first recognized in late 2019. Most early reports of person-to-person SARS-CoV-2 transmission have been among household contacts, where the secondary attack rate has been estimated to exceed 10% (1), in health care facilities (2), and in congregate settings (3). However, widespread community transmission, as is currently being observed in the United States, requires more expansive transmission events between nonhousehold contacts. In February and March 2020, the Chicago Department of Public Health (CDPH) investigated a large, multifamily cluster of COVID-19. Patients with confirmed COVID-19 and their close contacts were interviewed to better understand nonhousehold, community transmission of SARS-CoV-2. This report describes the cluster of 16 cases of confirmed or probable COVID-19, including three deaths, likely resulting from transmission of SARS-CoV-2 at two family gatherings (a funeral and a birthday party). These data support current CDC social distancing recommendations intended to reduce SARS-CoV-2 transmission. U.S residents should follow stay-at-home orders when required by state or local authorities.

Community-Based Testing for SARS-CoV-2 - Chicago, Illinois, May-November 2020.

On May 13, 2020, Chicago established a free community-based testing (CBT) initiative for SARS-CoV-2, the virus that causes COVID-19, using reverse transcription-polymerase chain reaction (RT-PCR). The initiative focused on demographic groups and geographic areas that were underrepresented in testing by clinical providers and had experienced high COVID-19 incidence, including Hispanic persons and those who have been economically marginalized. To assess the CBT initiative, the Chicago Department of Public Health (CDPH) compared demographic characteristics, economic marginalization, and test positivity between persons tested at CBT sites and persons tested in all other testing settings in Chicago. During May 13-November 14, a total of 253,904 SARS-CoV-2 RT-PCR tests were conducted at CBT sites. Compared with those tested in all other testing settings in Chicago, persons tested at CBT sites were more likely to live in areas that are economically marginalized (38.6% versus 32.0%; p<0.001) and to be Hispanic (50.9% versus 20.7%; p<0.001). The cumulative percentage of positive test results at the CBT sites was higher than that at all other testing settings (11.1% versus 7.1%; p<0.001). These results demonstrate the ability of public health departments to establish community-based testing initiatives that reach communities with less access to testing in other settings and that experience disproportionately higher incidences of COVID-19.

Data-Driven Reopening of Urban Public Education Through Chicago's Tracking of COVID-19 School Transmission.

Reopening in-person education in public schools during the coronavirus 2019 (COVID-19) pandemic requires careful risk-benefit analysis, with no current established metrics. Equity concerns in urban public schools such as decreased enrollment among largely Black and Latinx prekindergarten and special needs public school students already disproportionately impacted by the pandemic itself have added urgency to Chicago Department of Public Health's analysis of COVID-19 transmission. Close tracking within a large school system revealed a lower attack rate for students and staff participating in in-person learning than for the community overall. By combining local data from a large urban private school system with national and international data on maintaining in-person learning during COVID-19 surges, Chicago believes in-person public education poses a low risk of transmission when the operational burden imposed by the second wave has subsided.

Risk Factors for Severe Acute Respiratory Syndrome Coronavirus 2 Infection in Homeless Shelters in Chicago, Illinois-March-May, 2020.

BACKGROUND: People experiencing homelessness are at increased risk of coronavirus disease 2019 (COVID-19), but little is known about specific risk factors for infection within homeless shelters. METHODS: We performed widespread severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) polymerase chain reaction testing and collected risk factor information at all homeless shelters in Chicago with at least 1 reported case of COVID-19 (n = 21). Multivariable, mixed-effects log-binomial models were built to estimate adjusted prevalence ratios (aPRs) for SARS-CoV-2 infection for both individual- and facility-level risk factors. RESULTS: During March 1 to May 1, 2020, 1717 shelter residents and staff were tested for SARS-CoV-2; 472 (27%) persons tested positive. Prevalence of infection was higher for residents (431 of 1435, 30%) than for staff (41 of 282, 15%) (prevalence ratio = 2.52; 95% confidence interval [CI], 1.78-3.58). The majority of residents with SARS-CoV-2 infection (293 of 406 with available information about symptoms, 72%) reported no symptoms at the time of specimen collection or within the following 2 weeks. Among residents, sharing a room with a large number of people was associated with increased likelihood of infection (aPR for sharing with >20 people compared with single rooms = 1.76; 95% CI, 1.11-2.80), and current smoking was associated with reduced likelihood of infection (aPR = 0.71; 95% CI, 0.60-0.85). At the facility level, a higher proportion of residents leaving and returning each day was associated with increased prevalence (aPR = 1.08; 95% CI, 1.01-1.16), whereas an increase in the number of private bathrooms was associated with reduced prevalence (aPR for 1 additional private bathroom per 100 people = 0.92; 95% CI, 0.87-0.98). CONCLUSIONS: We identified a high prevalence of SARS-CoV-2 infections in homeless shelters. Reducing the number of residents sharing dormitories might reduce the likelihood of SARS-CoV-2 infection. When community transmission is high, limiting movement of persons experiencing homelessness into and out of shelters might also be beneficial.