Scientific Publications

This study documents the operational challenges and strategic decisions involved in sustaining a modeling-driven state public health dashboard — the California Communicable Diseases Assessment Tool (CalCAT) — across the evolving phases of the COVID-19 pandemic and beyond. Lessons include adaptive model selection, stakeholder communication, and transitioning from crisis-mode to sustainable infrastructure.

This paper presents a framework for estimating the effective reproduction number (Rt) of SARS-CoV-2 in real-time using county-aggregated wastewater surveillance data from California. The approach leverages wastewater concentration trends as leading indicators of transmission dynamics, enabling timely public health response without relying solely on clinical case counts. Models were validated against known variant waves and hospitalization data across California's largest sewersheds.

This study evaluates the performance of wastewater-based epidemiology as a sentinel surveillance tool for Omicron sub-variant detection across California. The analysis demonstrates that wastewater signals reliably preceded clinical case surges, providing actionable lead-time for public health response during rapidly evolving variant landscapes.

This paper quantifies the strength and timing of correlations between SARS-CoV-2 wastewater concentrations and clinical case incidence rates across California's National Wastewater Surveillance System (NWSS) sewersheds, spanning Delta, Omicron BA.1, and Omicron BA.2/BA.5 variant periods. Results highlight how the wastewater-to-case correlation shifted across variants and over the course of the pandemic.

This study uses ddPCR and sequencing of wastewater samples from two major metropolitan sewersheds to estimate the relative prevalence of SARS-CoV-2 variants (Delta and Omicron). It demonstrates the utility of wastewater genomic surveillance as an early, population-level indicator of variant emergence — preceding clinical surveillance by several days.