  The rapid spread of the new SARS-CoV-2 virus triggered a global health crisis
disproportionately impacting people with pre-existing health conditions and
particular demographic and socioeconomic characteristics. One of the main
concerns of governments has been to avoid the overwhelm of health systems. For
this reason, they have implemented a series of non-pharmaceutical measures to
control the spread of the virus, with mass tests being one of the most
effective control. To date, public health officials continue to promote some of
these measures, mainly due to delays in mass vaccination and the emergence of
new virus strains. In this study, we studied the association between COVID-19
positivity rate and hospitalization rates at the county level in California
using a mixed linear model. The analysis was performed in the three waves of
confirmed COVID-19 cases registered in the state to September 2021. Our
findings suggest that test positivity rate is consistently associated with
hospitalization rates at the county level for all waves of study. Demographic
factors that seem to be related with higher hospitalization rates changed over
time, as the profile of the pandemic impacted different fractions of the
population in counties across California.
