The pandemic equation

A candlelit counting house at night. Four clerks in dark robes work along a scarred table: one weighs a caged rat on a brass balance, one lifts something from a glass jar with tweezers, one draws coloured threads across a chart, and one rules columns in a huge ledger. On the slate behind them, rats plus fleas plus coins, with the signs beneath it crossed out and redrawn. Through the window a ship lies at a wharf and rats come ashore along its mooring chain. In the middle of the table a rat stands on the papers beside a spilled inkwell.

An insurance premium is a number. So is a budget line, and so is a ranking of countries by preparedness. Pandemic risk arrives as a sentence, and the quantities that would turn it into a number sit in wildlife samples, hospital records, flight schedules and four centuries of death counts, in different fields and different units.

Disclaimer

No rats were harmed in the writing of these pages, and several were consulted. The figures within carry error bars wide enough to shelter a small colony, and the observatory accepts no liability for anything that came ashore along the mooring chain while the clerks were busy counting it. Wash your hands. The ledger will not be washing its own.