its specificity is very low - equal to the prevalence rate of the disease.

It’s actually 0. The specificity of a test is the probability of a negative test given the absence of disease. Since the probability of a negative test is 0 in this example, it is also 0 given the absence of disease.

It’s actually 0. The specificity of a test is the probability of a negative test given the absence of disease. Since the probability of a negative test is 0 in this example, it is also 0 given the absence of disease.