LB-12. SARS-CoV-2 RNA and Antibodies among People Experiencing Homelessness and Staying in Shelters or Outdoor Encampments in Denver, Colorado, May-July 2020

BACKGROUND: The COVID-19 pandemic has disproportionately affected people experiencing homelessness (PEH) residing in shelters. Initial and regular testing of PEH in communities with moderate or substantial SARS-CoV-2 transmission may limit spread in shelters. We analyzed factors associated with positive SARS-CoV-2 RNA and antibody tests for PEH staying in shelters or encampments in Denver, Colorado. METHODS: In May 2020, Denver Public Health collaborated with local leaders to identify 4 homeless shelters and 3 outdoor encampments for voluntary, universal SARS-CoV-2 testing. At each testing event, a short questionnaire including sociodemographic factors and symptoms was administered to PEH who consented to testing. SARS-CoV-2 RNA testing by reverse transcription polymerase chain reaction (RT-PCR) was performed on nasopharyngeal swabs; antibody testing was performed on venous blood samples. PEH reporting a prior positive RT-PCR test were not retested but were eligible for antibody testing. Statistical calculations were performed with an α of 0.05; all tests were two-sided. RESULTS: From June 2–July 28, 2020, 931 PEH were approached. A total of 863 RT-PCR tests were performed at 14 testing events, and 334 antibody tests were performed at 5 testing events. Overall, 604 and 259 RT-PCR tests were conducted in 4 shelters and 3 encampments, respectively; 189 and 145 antibody tests were conducted in 3 shelters and 2 encampments, respectively. PEH tested in shelters were older, more often men, less often Native American, and less likely to report COVID-19 symptoms than those tested at encampments (Table 1). Overall, 9% of PEH tested in shelters tested positive for SARS-CoV-2 compared to 3% of PEH tested in encampments (p=0.002); 8% of men had positive RT-PCR results compared to 2% of women (p=0.03) (Table 2). PEH tested at shelters had a higher percentage of detectable SARS-CoV-2 antibodies than those tested in encampments (24% vs 8%, p=0.0002; Table 3). Neither RT-PCR nor antibody test results differed significantly by race or ethnicity. Table 1. Demographics of participants residing in encampments compared with shelters in Denver, Colorado, May-July 2020 (n=931) [Image: see text] Table 2. Comparison of participants testing positive or negative for SARS-CoV-2 RT-PCR* by location and demographics, in Denver, Colorado, May-July 2020 [Image: see text] Table 3. Comparison of participants testing positive or negative for antibodies against SARS-CoV-2 by location and demographics in Denver, Colorado, May-July 2020 [Image: see text] CONCLUSION: A greater percentage of PEH tested positive for both SARS-CoV-2 RNA and antibodies at shelters than encampments, suggesting that continued assessment of mitigation strategies in shelters should be a priority. DISCLOSURES: All Authors: No reported disclosures