Current Status and a Future Perspective of COVID-19 in Egypt: Egyptian Reference Laboratory Experience

Comparative Evaluation of Different SARS-CoV-2 Rapid Point-of-Care Antigen Tests with SARS-CoV-2 PCR for Diagnosis of COVID-19

BACKGROUND: Detection of positive 2019-nCoV nucleic acids by real-time reverse transcriptase-polymerase chain reaction (rRT-PCR)-based assays performed on the upper and lower respiratory samples remains the gold standard for the diagnosis of COVID-19. However, antigen-detecting rapid diagnostic tests can offer a faster (15–30 min) and less expensive way to diagnose active severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection than nucleic acid amplification tests. AIM: Hence, the present study aimed to compare and evaluate the results of different SARS-CoV-2 rapid point-of-care antigen tests with SARS-CoV-2 PCR as a reference method. METHODS: Sixty-five nasopharyngeal swab specimens were collected from attendees of the Reference Laboratory of Egyptian university hospitals. The samples were placed in viral transport medium for RNA extraction. The remaining part of the suspension was stored at −70°C until use for COVID-19 antigen testing. All samples were processed for the COVID-19 Ag rapid test and RT-PCR simultaneously. RESULTS: RT-PCR assay revealed 46 (70.8%) positive samples and 19 (29.2%) negative samples for COVID-19. All eight rapid antigen assays indicated specificity and positive predictive value of 100% each. As for the other parameters, the sensitivity, negative predictive value (NPV), and accuracy ranged from 43.8 to 93.8, 33.3 to 90, and 60 to 96, respectively. Biozak exhibited the best performance with the highest sensitivities 91.3, 81.8, and 93.75, respectively, while Viro and Standard Q were the worst among the tested kits with sensitivity, NPV, and accuracy of 50, 33.3, and 60 each. Regarding the relationship between the viral load of COVID-19 detected by RT-PCR and the results of the eight rapid antigen tests (RAT), we deduced that the higher the viral load, the better the sensitivity observed. CONCLUSION: The RATs used, in our study, exhibited heterogeneous diagnostic performance, where some of them showed very promising results in comparison to the reference RT-PCR assay.

Comparative Evaluation of SARS-CoV-2 Rapid Immunochromatographic Test Assays with Chemiluminescent Immunoassay for the Diagnosis of COVID-19

Background To date, the molecular assay is the gold-standard method for COVID-19 diagnosis. However, they are expensive and complex. There is a pressing necessity for developing other effective diagnostics for SARS‐CoV‐2 patients. Therefore, serological detection of antibodies against SARS‐CoV‐2 might provide a good alternative. Aim We aimed to compare and evaluate seven rapid diagnostic tests with Mindray chemiluminescent automated immunoassay as a reference method for SARS-CoV-2 antibodies detection. Methods: This study included the serum of a total of 49 attendees to the Reference Laboratory of Egyptian university hospitals during the period from April 2021 to May 2021. Anti-Covid-19 antibodies detection in serum samples was performed by Mindray fully automated system as our reference method and seven rapid antibody tests; Wondfo, Vazyme, Dynamiker, Panbio, Artron Maccura and Roche. Results: The chemiluminescent assay revealed 30 (61.2%) positive samples and 19 (38.8%) negative samples for COVID-19 IgG. For COVID-19 IgM, 11 (22.4%) samples were positive and 38 (77.6%) samples were negative. Anti-SARS-CoV-2 antibodies were not detected in any of the PCR negative individuals. The best diagnostic performance was demonstrated by Roche IgG and IgM, and Vazyme IgG and IgM antibody tests followed by Panbio. For Roche, the sensitivity and specificity for IgG and IgM were (83.3%, 89.5%) and (72.7%, 81.6%) respectively. Vazyme showed sensitivity and specificity for IgG and IgM were (77.8%, 85.7%) and (75%, 91.7%) respectively. Regards Panbio, the sensitivity and specificity for IgG and IgM were (63.6%, 87.5%) and (50%, 86.7%) respectively. Cohen’s Kappa values revealed a substantial agreement for Roche IgG, Vazyme IgG and IgM of (0.7076, 0.6250, 0.6667) respectively. The worst agreement was reported for Maccura IgG, Wondfo, and Dynamiker IgM with Cohen’s Kappa values of (0.2508, 0.1893, 0.0313) respectively. Conclusions: Rapid tests in our study exhibited heterogeneous diagnostic performances. Roche, Vazyme, and Panbio antibody tests showed promising results in concordance with our reference method with the best-reported results. On the other hand, the other tests were inferior and failed in providing valid and reliable results. Further studies are necessary to determine the practicality of these tests in different settings and communities.