Seroprevalence of SARS-CoV-2-specific neutralizing antibodies in COVID-19 pneumonia patients

Aim: The aim is to know the seroprevalence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-specific neutralizing antibody responses in COVID-19 pneumonia patients and correlation of antibody titer values with COVID-19 pneumonia Category, cyclic threshold values of COVID-19 reverse transcription polymerase chain reaction (RT-PCR) test, and computed tomography (CT) chest severity score. Material and Methods: Using serologic assay, SARS-CoV-2 antibody titers were measured in 65 patients with COVID-19 pneumonia symptoms with either positive or negative COVID-19 RT-PCR tests and radiological changes in CT chest during COVID-19 Pandemic period. About 3–5 ml of venous blood was collected and blood samples were tested using Abbott SARS-COV 2 immunoglobulin G (IgG) assay. This assay detects IgG Antibody against SARS-CoV-2 nucleocapsid protein and has a sensitivity of 100% and a specificity of 99.6%. Sixty-five patients were enrolled for this study and their clinical data, comorbid conditions, laboratory RT-PCR test reports, SARS-COV-2 antibody titers, and CT chest severity score were assessed cross-sectionally. Results: The study was done on 65 hospitalized patients. Among them, 39 were male (60.9%) and 25 were female (39.1%). Most common comorbidities among them were systemic hypertension (16.7%), chronic obstructive pulmonary disease (36.1%), diabetes mellitus (5.6%), coronary artery disease (22.2%), and bronchial asthma (27.8%). Among 65 patients, 36 (56.3%) tested COVID-19 RT-PCR positive and 28 (43.8%) tested COVID-19 RT-PCR negative. 24 patients belong to category B1 (55.8%), 11 patients belong to category B2 (25.6%), and 8 patients belong to category C (18.6%). A high seroprevalence of SARS-CoV-2 IgG antibody after 2 weeks were observed-17% among Category B1 patients, 26% among Category B2 patients, and 43% among category C patients. CT chest severity score was correlated with serum antibody titers by Pearson correlation which revealed a positive correlation that is statistically significant (0.01). Cycle Threshold value of COVID-19 RT-PCR reports was correlated with serum antibody titers by Pearson correlation which revealed a negative correlation that is statistically insignificant. Conclusion: This study found a high seroprevalence of SARS-CoV-2 specific IgG antibodies among COVID-19 pneumonia patients and positive correlation of antibody titers with clinical COVID-19 pneumonia category and with CT Chest Severity score.