The Additional Contribution of Second Nasopharyngeal PCR to COVID-19 Diagnosis in Patients with Negative Initial Test

The World Health Organization (WHO) recommends performing a second test in patients with a high suspicion of novel coronavirus disease (COVID-19) whose first PCR test is negative. However, the additional contribution of the second PCR test to the diagnosis is unknown.

In this study, we aimed to investigate the contribution of second SARS-CoV-2 PCR to diagnosis in patients with a suspicion of COVID-19 whose initial test was negative.

A total of 1449 patients were hospitalized in infectious disease clinics with the suspicion of COVID-19 infection during the study period. We performed the second PCR test (697 nasopharyngeal sample, 5 tracheal aspirate) in 702/766 (91.6%) patients whose first tests were negative and detected as positive in only 6.6% (46) of samples.

The strategy of using the second nasopharyngeal PCR test to confirm or exclude the diagnosis seems to cause the loss of labor and time, and is costly, because its additional contribution to the first test is very low.