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When Worlds Collide

A Hybrid Epidemiologist and Laboratory Professional’s Perspective on COVID-19 Testing Data - W. Jon Windsor MLS (ASCP)cm, MPH-Epidemiology Epidemiologist, Consultant - University of Colorado

Being both a medical laboratory scientist (MLS) and an epidemiologist during a pandemic is an interesting and humbling experience. My MLS background equipped me with the knowledge and experience to perform and understand the diagnostic tests that epidemiologists rely on to conduct infectious disease surveillance. Being a participant for both disciplines has enlightened me to the nuances of COVID-19 testing—and how epidemiologists interpret those results in the United States.

Medical Laboratory Science and COVID-19 Laboratory Testing

As an MLS, I learned that diagnostic tests have varying methodologies that communicate very different information. For instance, a polymerase chain reaction (PCR) diagnostic test will identify the presence of COVID-19’s genetic material, meaning a person with symptoms has an active COVID-19 infection. Whereas a serology test will identify COVID-19 antibodies, which tells us an individual had a previous infection. Going further, we learn that different result combinations of both methods will communicate even more information (Fig. 1).

Case Definitions, Data Interpretation, and Epidemiology

My epidemiology experience taught me different ways to interpret the data surrounding COVID-19 cases. For example, we define ‘case definition’ as the who, what, when, and where of an infectious disease event that is commonly used for outbreak investigations; the ‘why’ usually comes after the outbreak. Epidemiology then uses the case definition to separate COVID-19 cases into different categories to help estimate the burden of disease and monitor the pandemic in real time. Within those categories, we define ‘incidence’ as the number of new COVID-19 cases, and ‘prevalence’ as the number of new AND previous COVID-19 cases. Note that this is a subtle yet important distinction.


In mid-April, the Council of State and Territorial Epidemiologists (CSTE) in the United States (US) published new COVID-19 guidance with a standardized COVID-19 case definition. The CDC and other State Health authorities adopted the new guidance. Figure 2 outlines those criteria.

See Figure 2 and the rest of this article in the Summer 2020 ADVOCATE, with perspectives from the medical laboratory professionals behind the mask fighting COVID-19: setting up a lab for testing, epidemiology perspectives on working with lab professionals to flatten the curve, transitioning MLA/T education online. Coming soon to your mailbox or on our app! Contact us at to get the password.

1 Comment

Oct 05, 2020

In Covid-19, the population can relapse again after recovery is a great test for laboratory researchers.

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