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Study of COVID-19 infection rates among CHOC’s Emergency Department personnel suggests most got virus through community exposure

A team from CHOC has published original research on the prevalence of COVID-19 infection among its Emergency Department workers during the early stages of the pandemic.

A key finding of the study, called PASSOVER (Provider Antibody Serology Study of Virus in the Emergency Room), suggests that most infections were transmitted through community exposure rather than co-workers, although the study stopped short of drawing a definitive conclusion based on the relatively small sample size of workers who agreed to be tested for SARS-CoV-2.

Researchers observed a seroconversion rate of about one new positive case every two days during the period from April 14-May 13, 2020, during which 143 CHOC ED personnel were repeatedly tested for the virus. They included doctors, physician assistants, nurse practitioners, nurses, medical technicians, secretaries, monitor technicians, and additional administrative staff.

“The acquisition of seropositivity in our study group appeared to follow a linear trend, which is not consistent with the exponential rate of growth that would be expected for transmission within a closely interacting group of people,” the study concludes.

The research project, the results of which were electronically published on April 9, 2021 in the Western Journal of Emergency Medicine, was led by Dr. Theodore Heyming, chair of emergency medicine at CHOC, and Dr. Terence Sanger, a physician, engineer, and computational neuroscientist and vice president, chief scientific officer at CHOC, and vice chair of research for pediatrics at the UCI School of Medicine. The other co-authors of the study are John Schomberg, PhD, CHOC’s Department of Nursing; and Aprille Tongol, Kellie Bacon, and Bryan Lara, all of CHOC’s Research Institute.

The study noted that there is limited data that is publicly available on the seroprevalence of SARS-CoV-2 among healthcare workers. Another of the report’s key findings was that rapid antibody testing may be useful for screening for SARS-CoV-2 seropositivity in high-risk populations such as healthcare workers in the ED.

In the CHOC study, blood samples were obtained from asymptomatic ED workers by fingerstick at the start of each shift from April 14-May 13, 2020. Each worker’s blood sample was obtained every four days until the end of the study period. In addition, a nasopharyngeal swab (NPS) was collected from each participant on the date of study entry.

At the time of the study, 35 percent of the participants had known exposure to a COVID-19-positive individuals within the preceding five days.

Depending on the method used for analysis, the seroprevalence of SARS-CoV-2 among CHOC’s pediatric ED workers ranged from 2 percent to 10.5 percent – levels that were slightly higher than those reported for the local general population, the study found.

“This study would benefit from replication at additional sites that draw from larger samples of ED staff,” the report says.

Learn more about CHOC’s COVID-19 vaccine clinic.