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Attack rate

Statistic in epidemiology

Wikipedia contributorsAdapted for Fathomly · View authors
1 min read
Source updated February 7, 2026

In epidemiology, the attack rate is the proportion of an at-risk population that contracts the disease during a specified time interval. It is used in hypothetical predictions and during actual outbreaks of disease. An at-risk population is defined as one that has no immunity to the attacking pathogen, which can be either a novel pathogen or an established pathogen. It is used to project the number of infections to expect during an epidemic. This aids in marshalling resources for delivery of medical care as well as production of vaccines and/or anti-viral and anti-bacterial medicines.

The rate is arrived at by taking the number of new cases in the population at risk and dividing by the number of persons at risk in the population.

{\mbox{attack rate}}={\frac {\mbox{number of new cases in the population at risk}}{\mbox{number of persons at risk in the population}}}
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This article is adapted from the Wikipedia article “Attack rate”, written by its contributors and licensed under CC BY-SA 4.0. Fathomly has changed the layout, removed citation markers, navigation and maintenance notices, and adjusted punctuation. This adapted version is shared under the same license. For references, see the original article.

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