CD40LG and COVID-19: Using IgG-IgM based ELISA test which had the best overall diagnostic accuracy as an example, one can see that with 1000 patients and a COVID-19 prevalence of 50%, we would expect 432 (95% CI 394-486) patients to test positive for SARS-CoV-2, of which 427 (95% CI 393-451) will be true positives (are diseased and test positive) and 5 (95% CI 1-35) will be false positives (are not diseased but test positive).