The uncertainty in effective reproduction number estimation from heterogeneous case reporting

The effective reproduction number ( R t ) is a pivotal metric for tracking epidemic dynamics and informing public health interventions. However, its estimation is often compromised by heterogeneous case reporting, where factors such as limited testing capacity and surveillance delays cause reported cases to systematically deviate from true infection incidence. This study quantifies the uncertainty in R t estimation introduced by such heterogeneity across varying detection scenarios. We demonstrate that compared to the benchmark R t values from actual infections, estimates derived from reported data are: biased downward during the ascending phase of an outbreak; biased upward during the descending phase; and unbiased during stable periods. Our findings provide a framework for assessing the reliability of R t estimates and underscore the need for robust reporting systems.