PCR tends to have great specificity and great in vitro sensitivity. The sensitivity drops off with pre-analytic errors that accumulate in real world testing (wr

PCR tends to have great specificity and great in vitro sensitivity. The sensitivity drops off with pre-analytic errors that accumulate in real world testing (wrong collection method, wrong media, wrong swab, etc). So false negatives are the problem. The nice thing is that it catches acute infections even earlier than IgM.