Optimized Laboratory Detection Strategy for COVID-19 Patients Reduces the Rate of Missed Diagnosis

Abstract

Background: Novel coronavirus pneumonia (NCP) is an emerging, highly contagious community acquired pneumonia (CAP) caused by severe acute SARS-CoV-2. Nucleic acid test currently played a crucial role in diagnosis of suspected COVID-19 patients. However, a high false-negative rate of this “gold standard” test has been reported and posed a major setback in blocking the spread of the virus. We here aim to describe an optimized laboratory detection strategy to reduce the false negative rate. Methods: Suspected NCP patients were asked to collect both coughed up specimen and pharyngeal swab. Samples from the same patient were mixed and tested at a single pool. SARS-CoV-2 was then detected by real-time RT-PCR using two different detection kits. Only if both results were negative was the test reported as negative. The patients will be excluded after two consecutive negative tests at 24 hour intervals. We also used multiplex PCR to detect 13 common respiratory tract pathogens (RTP). Results: Using this strategy, we confirmed 85 SARS-CoV-2 infections from 181 suspected patients, and 94.12% of patients were positive in the first test. The 96 excluded patients were followed up, and no additional NCP was found. We also found that 31.25% patients in 96 non-NCP patients were infected with at least one RTP that may cause CAP. Conclusion: Our studies suggest that dual reagents screening with pooled coughed up specimen and pharyngeal swab samples reduced the false negative rate of nucleic acid testing. During the epidemic of NCP in Anhui province, there was a certain proportion of infection and co-infection of other common pathogens of CAP. In comparison with SARS-CoV-2 detection alone, combining multiple pathogen detection reduces the rate of miss diagnosis.