How Londoners tracked death figures to survive the Great Plague of 1665

"New research has uncovered how Londoners reacted in real time to the Great Plague of 1665, revealing that people reshaped their daily lives around published death figures - using them to decide where to go, who to meet, and whether to remain in the city or flee. The study, from the University of Portsmouth, shows that weekly death reports, known as the Bills of Mortality, served as a practical guide to survival."

"This day, much against my Will, I did in Drury-lane see two or three houses marked with a red cross upon the doors, and 'Lord have mercy upon us' writ there - which was a sad sight to me, being the first of that kind that to my remembrance I ever saw. (7th June 1665). The findings provide a rare, ground-level view of how people lived through a public health emergency centuries before modern medicine, and reveal striking parallels with how data is used today during health outbreaks to shape both policy and personal decision-making."

""Pepys wasn't just recording history, he was using death figures to decide how to live," said Professor Karen McBride of the University of Portsmouth. "His diary shows us, week by week, how published death numbers shaped fear, behaviour, and trust in government. It's one of the earliest examples of data being used to manage both populations and personal risk.""

Weekly death reports known as the Bills of Mortality served as practical guides for Londoners during the 1665 Great Plague. People reshaped daily routines around published death figures, using them to decide where to go, who to meet, and whether to remain in the city or flee. Samuel Pepys's diary records individual responses and the marking of infected houses. Rising death counts justified extraordinary government measures such as quarantine, travel restrictions, and suspension of everyday freedoms. The published numbers influenced fear, behavior, and trust in authorities. The episode offers a ground-level view of public health decision-making and parallels modern data-driven outbreak responses.

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