The performance of the SARS-CoV-2 RT-PCR test as a tool for detecting SARS-CoV-2 infection in the population
In light of our findings that more than half of individuals with positive PCR test results are unlikely to have been infectious, RTPCR test positivity should not be taken as an accurate measure of infectious SARS-CoV-2 incidence. Our results confirm the findings of others that the routine use of “positive” RT-PCR test results as the gold standard for assessing and controlling infectiousness fails to reflect the fact “that 50-75% of the time an individual is PCR positive, they are likely to be post-infectious”.
Asymptomatic individuals with positive RT-PCR test results have higher Ct values and a lower probability of being infectious than symptomatic individuals with positive results. Although Ct values have been shown to be inversely associated with viral load and infectivity, there is no international standardization across laboratories, rendering problematic the interpretation of RT-PCR tests when used as a tool for mass screening.