Enter the number of people who contracted a disease after a specific event and the total number of people expose to the event to determine the attack rate.

Attack Rate Formula

The following formula is used to calculate an attack rate. 

A = NC / PE
  • Where A is the attack rate
  • #NC is the number of cases of a disease in people exposed to a specific event
  • #PE is the number of people exposed to the specific event

To calculate an attack rate, divide the number of cases in people exposed by the total number of people exposed.

Attack Rate Definition

An attack rate is defined as the ratio of people that because sick after being exposed to a disease to the number of people exposed.

Attack Rate Example

How to calculate an attack rate?

  1. First, determine the number of cases of a disease in people exposed.

    Calculate the number of people that contracted the disease.

  2. Next, determine the number of people exposed.

    Measure the total number of people exposed.

  3. Finally, calculate the attack rate.

    Calculate the attack rate using the equation above.

FAQ

What is attack rate?

The attack rate is a medical term used to describe the proportion of people who became sick after being exposed to a specific event.