447. COVID-19 Prevalence Among COVID-19 Exposed Health Care Workers at a Tertiary Care Center in San Bernardino County, Ca

Background We studied the prevalence of positive SARS-CoV2 antibody and positive SARS-CoV2 antigen among high risk health care workers at Loma Linda University Health System (LLUHS) who voluntarily obtained SARS-CoV2 antibody testing, and if indicated, antigen testing. The study determined that there is a significant decrease in the prevalence of SARS-CoV2 antigen among employees at LLUH compared to the community. Methods Employee Health and Occupational Medicine offered antibody testing to employees who were considered high risk, primarily working in the Coronavirus Disease 19 (COVID-19) designated units. We tested 658 subjects’ serum for the presence of IgM and IgG antibodies via the Nirmidas Qualitative SARS-CoV2 test. 29 subjects with a positive antibody test were subsequently tested for the presence of serum SARS-CoV2 antigen via PCR. Results There were 31 subjects who tested positive for IgM or IgG antibodies. 11 subjects had positive IgM with negative IgG. 3 subjects had negative IgM with positive IgG. 15 patients had positive IgM and positive IgG. 2 subjects had positive IgM with negative IgG, were subsequently retested, and then found to have positive IgM and positive IgG. Of those 31 subjects with a positive antibody test, 2 were not tested for the COVID-19 antigen, 1 had an inconclusive test, 23 tested negative, and 5 tested positive. Of those 5 positive for the antigen, 2 had symptoms and 3 did not report symptoms or did not use the symptom questionnaire. The community prevalence of positive SARS-CoV2 antigen in San Bernardino is 0.37%, as of June 16. The prevalence of positive SARS-CoV2 antigen among LLUH employees is 0.03% and the prevalence of positive antibody is 0.18%. The value of z is -7.3206, p is < .00001. Thus, the result is significant at p < .01. Conclusion The results of this testing supports the efficacy of the early protective measures that LLUHS implemented in preparation for the pandemic. Such protective measures include: mandated face masks, symptoms screening, testing for SARS-CoV2 antibody or antigen on patients admitted, a dedicated COVID-19 section of the emergency department as well as inpatient units, etc. Given the statistical significance of this study, the protective bundle can be used as a template for preventative measures for future pandemics. Disclosures All Authors: No reported disclosures