Objective: 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.

Patients and methods: 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.

Results: 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.

Conclusions: 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.

目的：世界卫生组织（WHO）建议对第一次 PCR 检测呈阴性的高度怀疑新型冠状病毒病（COVID-19）的患者进行第二次检测。然而，第二次 PCR 检测对诊断的额外贡献尚不清楚。

患者和方法：在这项研究中，我们旨在调查第二次 SARS-CoV-2 PCR 对初步检测为阴性的疑似 COVID-19 患者的诊断的贡献。

结果：研究期间共有 1449 名疑似 COVID-19 感染患者在传染病门诊住院。我们对 702/766 (91.6%) 名患者进行了第二次 PCR 检测（697 个鼻咽样本，5 个气管抽吸物），这些患者的第一次检测结果为阴性，仅在 6.6% (46) 个样本中检测为阳性。

结论：使用第二次鼻咽 PCR 检测来确诊或排除诊断的策略似乎会造成劳动力和时间的损失，而且成本高，因为它对第一次检测的额外贡献很低。