Analysis of Nucleic Acid and Antibody Detection Results for SARS-CoV-2 Infection.

BACKGROUND: Real-time polymerase chain reaction (RT-PCR) of virus nucleic acid test (NAT) has become the standard method to diagnose severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. However, there are still many limitations, especially the problem of the high false negative rate. Therefore, the aim of this study was to investigate the positive rate of SARS-CoV-2 NAT and evaluate the diagnostic performance of SARS-CoV-2 IgM and IgG antibody detection in novel coronavirus infection. METHODS: A total of 10309 suspected or high-risk cases of infection with SARS-CoV-2 in Wuhan Hubei, China, were tested for virus NAT by RT-PCR. Among those cases, 762 COVID-19 patients and 143 patients with non-COVID-19 who were tested for SARS-CoV-2 IgM and IgG during the NAT period were screened. The difference between the two test methods was analyzed using the chi-square test. RESULTS: The positive rate of 10309 cases was about 36% (95% CI: 33.39%-39.67%). SARS-CoV-2 was present in various types of specimens, and alveolar lavage fluid had the highest positive rate [52.38% (95% CI: 31.02-73.74)]. The clinical sensitivity of serum SARS-CoV-2 IgM and IgG was 77.17% (588/762) and 94.88% (723/762), respectively, and the clinical specificity was 93.71% (134/143) and 90.21% (129/143). The area under the curve (AUC) of SARS-CoV-2 IgG and combination of IgG with IgM were equally larger than IgM [0.973 (95% CI: 0.964-0.983) vs 0.930 (95% CI: 0.910-0.949)]. IgG antibody had the highest specificity [100.0% (95% CI: 100.00%-100.00%)] and sensitivity [94.0% (95% CI: 92.45%-95.55%)] when detected alone or in combination with IgM antibody. The total coincidence rate of SARS-CoV-2 antibodies detection and SARS-CoV-2 NAT for the diagnosis of SARS-CoV-2 infection was 92.04% (833/905). Among the 34 SARS-CoV-2 NAT-negative patients with clinical symptoms and CT imaging features, 29 (85.29%) patients were positive for SARS-CoV-2 IgM, and 31 (91.76%) were positive for IgG. CONCLUSION: SARS-CoV-2 NAT should be considered for many types of specimens, and the combined test of SARS-CoV-2 IgM and IgG can make up for the problem of missed NAT in COVID-19 patients.

Clinical characteristics of COVID-19 complicated with pleural effusion.

BACKGROUND: Epidemiological and clinical features of patients with corona virus disease 2019 (COVID-19) were well delineated. However, no researches described the patients complicated with pleural effusion (PE). In the present study, we aimed to clinically characterize the COVID-19 patients complicated with PE and to create a predictive model on the basis of PE and other clinical features to identify COVID-19 patients who may progress to critical condition. METHODS: This retrospective study examined 476 COVID-19 inpatients, involving 153 patients with PE and 323 without PE. The data on patients' past history, clinical features, physical checkup findings, laboratory results and chest computed tomography (CT) findings were collected and analyzed. LASSO regression analysis was employed to identify risk factors associated with the severity of COVID-19. RESULTS: Laboratory findings showed that patients with PE had higher levels of white blood cells, neutrophils, lactic dehydrogenase, C-reactive protein and D-dimer, and lower levels of lymphocytes, platelets, hemoglobin, partial pressure of oxygen and oxygen saturation. Meanwhile, patients with PE had higher incidence of severe or critical illness and mortality rate, and longer hospital stay time compared to their counterparts without pleural effusion. Moreover, LASSO regression analysis exhibited that pleural effusion, lactic dehydrogenase (LDH), D-dimer and total bilirubin (TBIL) might be risk factors for critical COVID-19. CONCLUSIONS: Pleural effusion could serve as an indicator for severe inflammation and poor clinical outcomes, and might be a complementary risk factor for critical type of COVID-19.