Class, race and other demographics determined the risk of COVID-19 infection and death among Orange County residents in 2020, a new study conducted by the University of California, Irvine found.
The findings, published in the journal Emerging Infectious Diseases, showed COVID-19 infections and deaths “quickly shifted” to lower income Hispanic and Asian populations when shelter-in-place and social distancing policies were mandated.
Researchers from UCI’s Program of Public Health drew testing and mortality data from the Orange County Health Care Agency between the first six months of the pandemic— March 1 to Aug. 16, 2020— and separate seroprevalence data from a population-based survey conducted July 10 and Aug. 16 the same year.
The population-based survey examined the seroprevalence—or prior exposure to the virus—of 2,979 participants at 11 drive-thru sites, 350 of whom tested seropositive.
Researchers also examined contextual factors, including education, income, ethnicity and “household crowding at the ZIP code level.”
“A pandemic is really made up of many local epidemics, each playing out according to local contextual factors,” Daniel Parker, professor of public health, infectious disease epidemiologist and author of the study, said in a statement.
“It’s important to understand and document local contextual factors associated with infectious disease outbreaks and the resulting disparities in morbidity, mortality and quality of life.”
The study concluded populations with higher household density, lower incomes, and less education were at higher risk of infection and death.
Additionally, Asians and Hispanics were more likely to die than whites, noting that 17.9% of Hispanics and 12% of Asians in Orange County live below the poverty line.
Consistent with other reports, the study also found older age groups and males to be at higher risk.
Parker also noted the study’s race and ethnicity categories of Hispanic and Asian were “too broad,” and it would be “highly beneficial” if future studies had more specific information.
“Our local Asian population is extremely diverse, and lumping them into a single category probably masks some important differences in risk of infection or death between different Asian populations,” he added.
The Quarantine Effect
Orange County’s dense and diverse population provided a unique opportunity to examine COVID-19’s epidemiological correlates, Parker said.
California was also one of the first states to mandate shelter-in-place policies, isolating data on essential workers outside the home for several months.
The data showed, at the pandemic’s onset in March 2020, cases clustered in the county’s higher-income, coastal areas, where residents were more likely to have travelled to out-of-town areas and caught the virus there.
By April, it “quickly shifted” to north-central locations, particularly Santa Ana and Anaheim.
“Persons who are independently wealthy or who work in occupations where working from home was a viable option, were more capable of practicing social distancing,” the study stated. “Persons from low socioeconomic status areas, by contrast, may have less ability to practice social distancing.”
Reasons for these findings were “likely complex and related to issues of accessing healthcare and general social determinants of health.”
To date, more that 5,200 people in Orange County have died from the virus. It is estimated that nearly 10% of the area’s population has caught the virus since early 2020.