Strategies to Estimate Prevalence of SARS-CoV-2 Antibodies in a Texas Vulnerable Population: Results from Phase I of the Texas Coronavirus Antibody REsponse Survey (TX CARES)

Valerio-Shewmaker, M. A.; Desantis, S. M.; Swartz, M. D.; Yaseen, A.; Gonzalez, M. O.; Kohl, H. W.; Kelder, S. H.; Messiah, S. M.; Aguillard, K. A.; Breaux, C. J.; Wu, L.; Lakey, D.; Shuford, J.; Pont, S.; Boerwinkle, E.

Introduction: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and immunity remains uncertain in populations. The state of Texas ranks 2nd in infection with over 2.71 million cases and has seen a disproportionate rate of death across the state. The TX CARES project was funded by the state of Texas to estimate the prevalence of SARS-CoV-2 antibody status in children and adults. Materials and Methods: The TX CARES (Texas Coronavirus Antibody Response Survey) is an ongoing prospective population-based convenience sample from the Texas general population that commenced in October 2020. Volunteer participants are recruited across the state to participate in a 3-time point data collection TX CARES to assess antibody response over time. We use the Roche Elecsys Anti-SARS-CoV-2 Immunoassay to determine SARS-CoV-2 antibody status. Results: The crude antibody positivity prevalence in Phase I was 26.1% (80/307). The fully adjusted seroprevalence of the sample was 31.5%. Specifically, 41.1% of males and 21.9% of females were seropositive. For age categories, 33.5% of those 18-34; 24.4% of those 35-44; 33.2% of those 45-54; and 32.8% of those 55+ were seropositive. In this sample, 42.2% (89/211) of those negative for the antibody test reported having had a COVID-19 test. Conclusions: In this first phase we enrolled and analyzed data for 319 participants, demonstrating a high survey and antibody test completion rate, and ability to implement a questionnaire and SARS-CoV-2 antibody testing within FQHC clinical settings. We were also able to determine our capability to estimate the cross-sectional seroprevalence within Texas FQHC clinical settings. The crude positivity prevalence for SARS-CoV-2 antibodies in this sample was 26.1% indicating potentially high exposure to COVID-19 for FQHC clinic employees and patients. These methods are being used to guide the completion of a large longitudinal survey in the state of Texas with implications for practice and population health.