437 - Asymptomatic Healthcare Worker COVID-19 Testing Program

Background: The SARS-CoV-2 pandemic remains a major threat worldwide. Healthcare workers (HCWs) are particularly impacted by the COVID-19 pandemic with high infection rates reported from HCWs in hard-hit regions^2,3, raising concerns about nosocomial infections and the effectiveness of personal protective equipment in protecting HCWs.  Asymptomatic infection is estimated 17.9% to 33.3%⁴ and is a common source of transmission⁵. 
We designed a HCW testing program to address patient and employee concerns about exposures in the healthcare setting at our 808-bed health system.  During the time of employee testing, the mean (range) number of inpatients with a diagnosis of COVID was 30 (22-38) of a mean (range) daily census of 560 (492-602) (approximately 5.4%).

Methods: This opt-in program offered SARS-CoV-2 testing of asymptomatic HCWs with paired nasopharyngeal or mid-turbinate swab for PCR (Roche) and serum IgG antibody testing (Diazyme).   While initially designed as a pilot project in the Emergency Departments and COVID-19 units, it was quickly expanded to a health system-wide initiative.

Results: From April 22 to June 2, PCR testing was performed on 5826 asymptomatic HCWs with four PCR tests resulting positive (0.09%).  Of 5589 serologic tests (anti-SARS-CoV-2 IgG) performed, 57 tested positive (1.02 %).  All HCW with a positive IgG had a concurrent negative PCR.

Conclusion: In this cross-sectional evaluation, the point prevalence of SARS-CoV-2 IgG in asymptomatic HCWs at UC San Diego was less than 1%, supporting modeling estimations at the San Diego County level of very low levels of community exposure at the time of this testing.
Further analyses of incidence rates and potential risk factors such as employee roles within the healthcare system, community and healthcare exposures, and home zip code are underway.
Asymptomatic HCW testing is a strategy that can provide the perception of additional safety to both the workforce and patients as the health system reopens, while potentially reduce transmission from asymptomatic persons through active case finding and isolation.