Plague Data: Londoners' Secret Survival Guide

In 1665, as the Great Plague ravaged London, residents did not rely solely on prayer or flight. New research by Professor Karen McBride suggests that the weekly Bills of Mortality functioned as an early public health information system, guiding Londoners' actions and survival strategies.

The published death figures were accessible, allowing citizens to track week-on-week changes in mortality rates by parish. Naval administrator Samuel Pepys meticulously recorded these totals in his diary, using the data to adjust his daily life. He rerouted his travel to avoid heavily affected areas, reconsidered social visits, and ultimately moved his wife out of the city as the numbers climbed.

McBride's study indicates these Bills enabled individuals to assess personal risk, influencing decisions about travel and when it was safe to return to the city. While literacy and the ability to act on this information were unequally distributed, the data fostered a sense of self-surveillance and self-governance. Even when inaccuracies were suspected, rising death tolls prompted caution, while falling numbers encouraged the resumption of normal social and economic activities.

The research challenges the notion of 17th-century society being passive in the face of disease, noting that practical measures like isolation and distancing were adopted, even if the underlying understanding of disease transmission differed from modern knowledge. However, the study also underscores the significant inequalities, as plague deaths among the poor were more likely to be misclassified or underreported, limiting their ability to respond effectively to the information provided.