From the Document: "This guidance is based on what is currently known about the transmission and severity of coronavirus disease 2019 (COVID-19). The California Department of Public Health (CDPH) will update this guidance as needed and as additional information becomes available. This document is intended to be statewide guidance to help both school and public health officials inform their decision making. Decisions by school officials and local public health officials should be determined by the specific circumstances in local jurisdictions."
California Department of Public Health
California Department of Public Health: https://www.cdph.ca.gov/