A letter arguing that early COVID cases without a documented Huanan-market link were, on average, closer to the market than cases with a confirmed market link — the reverse of what a simple model would predict if proximity to the market simply tracked true market exposure. Argues this pattern is better explained by systematic proximity-based ascertainment bias (investigators more likely to ask about, or successfully establish, a market link for cases already known to live/work near the market) than by a genuine spatial signal of market origin, undercutting the inferential basis of the Worobey 2022 geospatial claim.
relevance_note: the key formal ascertainment-bias argument against reading the geospatial clustering as evidence of market origin; flag the same-author overlap with this case’s own Bayesian-analysis record (slice G) when weighing it.