A hepatitis A epidemic produced 555 cases and 3 of the case-patients died. What is the case-fatality rate?

1. The case-fatality rate divides deaths among cases by the number of cases. 2. 3 divided by 555 equals 0.0054. 3. Multiplying by 100 gives 0.5%. 4. 5.4% and 54.1% slip the decimal point one and two places, the commonest error on small case-fatality figures. 5. 0.1% understates the same division by a further factor of five, so it too misreports a correct fraction. _Source: CDC Principles of Epidemiology in Public Health Practice (3rd ed., US federal, public domain), Lesson 3 "Measures of Risk", section Case-fatality rate_