The area under the curve represents the probability that the assay result for a randomly chosen positive case will exceed the result for a randomly chosen negative case. The asymptotic significance is less than 0.05, which means that using the assay is better than guessing. While the area under the curve is a useful one-statistic summary of the accuracy of the assay, you need to be able to choose a specific criterion by which blood samples are classified and estimate the sensitivity and specificity of the assay under that criterion. See the coordinates of the curve to compare different cutoffs.