Abstract

The emergence of SARS-CoV-2, responsible for coronavirus disease-2019 (COVID-19), has become a major global health problem. The molecular testing is the accepted assay in SARS-CoV-2 detection. However, there are several reasons for low sensitivity by RNA detection, causing challenges in SARS-CoV-2 diagnosis. In this study, we aimed to investigate serological patterns of SARS-CoV-2 specific IgM, and IgG in 111 hospitalized, and 34 recovered COVID-19 patients and 311 prepandemic normal serum specimens by ELISA. The validity of the ELISA kits was evaluated using samples from normal and recovered cases. This showed that 98.1, and 98.4 of prepandemic normal samples were negative for anti-SARS-CoV-2 IgM, and IgG, respectively. Assessment of 34 COVID-19 confirmed recovered patients showed a test sensitivity of 76.5, and 94.1 for IgM, and IgG, respectively. In COVID-19 hospitalized patients, 42.3, and 51.4 were positive for IgM and IgG, respectively. Viral RNA was not detectable in 43.3 of the hospitalized patients. Interestingly, combined molecular and serological testing improved the sensitivity of COVID-19 diagnosis to 79.6. Using PCR with combined IgM/IgG results augmented the patient diagnosis sensitivity to 65.3 and 87.2 in <= 7 days, and > 7 days intervals, respectively. Overall, serological tests in combination with PCR can improve the sensitivity of COVID-19 diagnosis.