Modeling the effectiveness of healthcare personnel reactive testing and screening for the SARS-CoV-2 Omicron variant within nursing homes

The SARS-CoV-2 Omicron variant has been hypothesized to exhibit faster clearance (time from peak viral concentration to clearance of acute infection), decreased sensitivity of antigen tests, and increased immune escape (the ability of the variant to evade immunity conferred by past infection or vaccination) compared to prior variants. These factors necessitate re-evaluation of prevention and control strategies—particularly in high-risk, congregate settings like nursing homes that have been heavily impacted by other COVID-19 variants. We used a simple model representing individual-level viral shedding dynamics to estimate the optimal strategy for testing nursing home healthcare personnel and quantify potential reduction in transmission of COVID-19. This provides a framework for prospectively evaluating testing strategies in emerging variant scenarios when data are limited. We find that case-initiated testing prevents 38% of transmission within a facility if implemented within a day of an index case testing positive, and screening testing strategies could prevent 30-78% of transmission within a facility if implemented daily, depending on test sensitivity.