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What does a relative risk of 1 indicate in an epidemiological study?

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Know the investigations of researchers using genomic information to reconstruct the cause and transmission routes of the bubonic plague and the Black Death — epidemiology Researchers using genomic information to trace the transmission routes in past epidemics of plague.

In epidemiology, a relative risk of 1 indicates that there is no association between the exposure and the outcome being studied.1

This measure is typically applied to categorical data from a cohort study by comparing the incidence of an event in an exposed group to the incidence in a baseline group. When the relative risk is exactly 1, it signifies that the risk of the outcome is the same in both the exposed and unexposed groups. Conversely, a relative risk other than 1 indicates an association, where values greater than 1 suggest an increased risk and values less than 1 suggest a protective effect.1