What is the prevalence of coronavirus infections in Jefferson County, Kentucky?

Supporting University of Louisville in estimating the rate of coronavirus infection in Jefferson County Kentucky over the course of the pandemic


One of the major challenges of the COVID-19 pandemic is understanding how the virus moves through populations over time.

The goal of this study for the University of Louisville is to provide COVID-19 antigen and antibody testing to a representative sample of individuals from different areas of Jefferson County, Kentucky, in proportion to the age and race of the population of the area.


Westat has supported 8 rounds of data collection. For each, we drew an address-based sample of households across 4 geographic areas within Jefferson County. The sampling approach changed over time to meet different requirements. For different rounds, criteria such as race, age, and sex were used and non-White residents were sampled at a higher rate. Later, areas were sampled to provide data to complement data collected from wastewater sampling.

Westat designed and mailed recruitment materials and reminders. The sampled household member was asked to complete a web-based screener and schedule a testing appointment. We weighted data and provided analytic support. A volunteer community-based sample was also tested and weighted.


Results are being used in a variety of analyses. A key result is showing where infection rates are highest within the county and which demographic groups are most highly infected. Official records are inadequate for this purpose because only those with the most serious symptoms are tested. The survey data shows rates of infection many times higher than the official data. Other analyses are examining correlates such as tobacco use and infection. Modeling is also being done in coordination with CDC to examine how the survey data tracks infections compared to data being collected from wastewater.


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