California Department of Public Health
In March 2020, early in the COVID-19 epidemic, I learned through the UC Berkeley statistics department that CDPH was looking for volunteers to aid in its COVID response. Mike Wilkening, advisor to the governor and head of the Office of Digital Innovation, and DJ Patil, former CTO under the Obama administration, were organizing a rapid response modeling team inside of CDPH to focus on forecasting and policy simulation. I was invited to join this team despite having no former background in public health.
The team collated COVID forecasts from academic research teams around the globe, integrating them into a public dashboard. I implemented and maintained the Simple Growth Model, which projected hospital utilization from current estimates of the reproduction number R, updating it as the epidemiological picture evolved. We collaborated with research groups to conduct simulations of policies related to vaccination strategies, school closures, and state hospitals. The modeling team was responsible for briefing state officials and local health officers about trends in the epidemic.
Publications
- COVID Testing in Schools — International Journal of Environmental Research and Public Health, 2022. Analysis of risk tradeoffs under different testing policies, done with colleagues at the CA Dept of Public Health and UCSF. Completed Spring/Summer 2021 with a view to safely reopening schools for the 2021–2022 school year.
- Racial and Ethnic Disparities in COVID-19 — Health Affairs, 2021. Analysis of racial and ethnic disparities in California for COVID-19 risk exposure, testing, and case rates. Co-authored with colleagues at CDPH and Stanford.
CalCAT
The California Communicable disease Assessment Tool (formerly the COVID Assessment Tool) is a dashboard I helped design and support for the California Department of Public Health. It aggregates forecasts from the health department and various academic research groups to track statewide disease trends.
- Keeping a Modeling-driven Public Health Dashboard Relevant — Frontiers in Public Health, 2025. Techniques to keep the California COVID modeling-based dashboard relevant as conditions and use-cases change.
Other Resources
- The Early Days of California's COVID Modeling — An article capturing the atmosphere of those early days, when volunteers from tech, academia, and public health came together to build forecasts quickly. I joined this team about a month after the events described.
- Ryan McCorvie on COVID-19 Forecasting — An interview discussing aspects of epidemiological modeling. (local copy)
- Contact Tracing Model — A simple Hawkes process model for contact tracing. The conclusion: for reasonable assumptions about infection rates and asymptomatic cases, contact tracing alone has a low probability of stopping spread.