A SARS-CoV-2 testing pipeline for COVID-19 health care workers

From the University of Washington and the Fred Hutch Vaccine and Infectious Disease Division

In January 2020, the Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic hit Seattle, Washington, which soon became the U.S. epicenter for the virus and its resulting COVID-19 disease. The surge in COVID-19 hospitalizations rendered health care workers (HCW) at especially high risk for exposure to SARS-CoV-2 while treating sick patients without sufficient PPE and inadequate COVID-19 testing. During similar pandemics, such as the 2003 SARS outbreak, HCW were disproportionately infected, but limited data exists on COVID-19 prevalence in HCW in 2020.  Drs. Nandita Mani, Jehan Budak, and Seth Cohen of the University of Washington (UW), along with collaborators from the Fred Hutch Vaccine and Infectious Disease Division, established a pipeline for rapid COVID-19 testing among Seattle HCW and published this work in Clinical Infectious Diseases. They then implemented this testing system to determine the prevalence of SARS-CoV-2 infection among Seattle HCW. As infected HCW could easily spread COVID-19 to their families, non-COVID patients, or other HCW, early detection of the virus is crucial to “better understand transmission risks, evaluate whether infection prevention policies are working, and ensure adequate staffing during the pandemic,” Dr. Mani said.

Two UW drive-through testing centers were established during the week of March 6th, where symptomatic UW Medicine HCW could use an online survey to request testing after the onset of potential COVID-19 symptoms. Nasopharyngeal swabs were collected and tested with PCR and results were returned via a secure online portal and phone calls.

Between March 12 and April 23, 2020, 3,477 symptomatic HCW were tested, and 185 (5.3%) tested positive for SARS-CoV-2, with prevalence increasing as the epidemic spread throughout Seattle.  Frontline HCW—defined as HCW who have face-to-face contact with patients—comprised 2,309 (66.4%) of the tested HCW, had SARS-CoV-2 prevalence of 5.2%. However, non-frontline HCW had a comparable prevalence of 5.5%. At 14 days-post diagnosis, follow-up with majority of tested HCW (94.1%) found that 6 HCW (3.2%) were hospitalized for COVID-19, 1 was admitted to the intensive care unit, all ultimately recovered, and 154 had returned to work without symptoms.

SARS-CoV-2 prevalence in Seattle UW Medicine non-frontline and frontline health care workers between March and April 2020.
SARS-CoV-2 prevalence in Seattle UW Medicine non-frontline and frontline health care workers between March and April 2020. Figure provided by Dr. Mani.

This work demonstrated that rapid, high throughput SARS-CoV-2 testing in HCW is feasible within a large hospital network, contributing to containment of viral spread. Efficient testing during pandemics can limit spread from infected HCW and inform PPE policies. Because frontline HCW might be expected to have higher rates of COVID-19, the comparable prevalence of SARS-CoV-2 infection between frontline and non-frontline HCW early in the pandemic suggests that HCW infections may have been acquired by community spread and not through patients, supporting current PPE requirements. Further studies are needed to understand the prevalence of SARS-CoV-2 in asymptomatic HCW. “As we increasingly test asymptomatic employees as part of contact tracing, we will be able to estimate the risk of developing COVID-19 following certain high-risk exposures both at work and in the community,” Dr. Cohen explained. “It’s not yet clear how COVID-19 rates among healthcare workers and other employees will be impacted as restrictions ease and community transmission increases. We will continue to collect data as the pandemic progresses, which will inform our policies and practices as we head into the winter season. In the future, we also hope to examine the subsequent serologic response of COVID-positive employees,” Dr. Cohen said.


 Fred Hutch/UW Cancer Consortium members Steven Pergam, Keith Jerome, and Catherine Liu contributed to this work.

Mani NS, Budak JZ, Lan KF, Bryson-Cahn C, Zelikoff A, Barker GEC, Grant CW, Hart K, Barbee CJ, Sandoval MD, Dostal CL, Corcorran M, Ungerleider HM, Gates JO, Olin SV, Bryan A, Hoffman NG, Marquis SR, Harvey ML, Nasenbeny K, Mertens K, Chew LD, Greninger AL, Jerome KR, Pottinger PS, Dellit TH, Liu C, Pergam SA, Neme S, Lynch JB, Kim HN, Cohen SA. 2020. Prevalence of COVID-19 Infection and Outcomes Among Symptomatic Healthcare Workers in Seattle, Washington. Clinical Infectious Diseases. doi: 10.1093/cid/ciaa761.