No evidence of systematic proximity ascertainment bias in early COVID-19 cases in Wuhan Reply to Weissman (2024)

In a short text published as Letter to the Editor of the Journal of the Royal Statistical Society Series A, Weissman (2024) argues that the finding that early COVID-19 cases without an ascertained link to Wuhan’s Huanan Seafood Wholesale market resided on average closer to the market than cases epidemiologically linked to it, reveals “major proximity ascertainment bias”. Here we show that Weissman’s conclusion is based on a flawed premise, and that there is no such “internal evidence” of major bias. The pattern can indeed be explained by places of infection not being limited to residential neighbourhoods, and by stochasticity – i.e., without requiring any ascertainment bias.