How accurate are prediction markets for predicting outbreaks?

Prediction markets are reasonably calibrated for events with abundant trading and public information, but they have limitations for novel disease outbreaks. Strengths: they aggregate diverse perspectives, update fast as new data arrives, and historically have outperformed expert panels on political and macro-economic forecasts. Weaknesses for outbreaks: (1) thin liquidity in early outbreak markets — a few traders can move prices substantially. (2) Resolution risk — what counts as an 'official pandemic declaration' may itself be disputed. (3) Information asymmetry — health authorities have private data traders don't. (4) Reflexivity — markets can become news, influencing the very thing they predict. The Polymarket 'Hantavirus pandemic 2026' market with $2.2M volume sits in a middle zone: enough liquidity to resist single-trader manipulation, but still volatile and sensitive to WHO statements.