What does “sensitivity” mean? What does “specificity” mean?

Sensitivity and specificity are different and complementary measures to inform doctors and patients about the accuracy of a test. A good test has both high sensitivity and high specificity.

  • Sensitivity is a measure of how well a test is able to detect people who are infected (positive cases). If a person has an infection, a test with 100% sensitivity can accurately detect it with a positive result. 
  • Specificity is a measure of how well a test can detect people who are NOT infected (negative cases). If a person does not have an infection, a test with a 100% specificity can accurately detect it with a negative result.