Extent of Unofficial Use of Exposure-Based Diagnostic Criteria in Early Wuhan COVID-19 Case Ascertainment

Determine the extent to which diagnostic criteria emphasizing contact with wet markets and contact with known COVID-19 cases were applied unofficially during stages of the early pandemic in Wuhan when such criteria were not part of the official case definition.

Background

The paper examines whether early geographic clustering of COVID-19 cases near the Huanan Seafood Market in Wuhan could be explained by proximity-based ascertainment bias rather than by true origin at the market. The author notes that official diagnostic criteria at various stages included exposure to wet markets and contact with known cases, conditions that could bias case detection toward areas near the market.

A key unresolved issue is how extensively these exposure-based criteria may have been used unofficially at other times, potentially shaping which cases were detected and reported. Quantifying any unofficial application is crucial for evaluating the reliability of spatial inferences about early case locations and the market’s role.