Community Health I & II Practice Test 2026 – Complete Exam Prep

The key distinction is that attack rate measures the risk of getting the disease in a defined population over a short time during an outbreak, while case fatality rate measures how deadly the disease is among those who have it. Attack rate counts new cases in a population at risk and divides by the at-risk population, often expressed as a percentage or per 1,000 or 100,000 people. Case fatality rate, on the other hand, is the proportion of deaths among identified cases, calculated as deaths divided by the number of identified cases. This reflects severity among those with the disease and depends on how thoroughly cases are detected and how long follow-up lasts. So the statement that attack rate measures the frequency of new cases during an outbreak and case fatality rate is the proportion of deaths among identified cases is the correct distinction.