Seroconversion in COVID-19 Infection and Comparison of Antibody Responses in Symptomatic Versus Asymptomatic Individuals

Abstract

Coronavirus disease (COVID-19) is an infectious disease caused by a newly discovered coronavirus. Following infection, antibodies are formed against the spike (S) and nucleocapsid (N) proteins, which are the primary viral antigens of SARS-CoV-2. This study aims to determine the antibody response three weeks post-infection and its persistence. To study antibody responses in COVID-19-positive individuals and to compare the degree of antibody response in symptomatic and asymptomatic individuals. The persistence of the antibody response was also assessed. Adult patients (> 15 years of age) who were diagnosed as COVID-19-positive by RT-PCR, three weeks after swab positivity were tested for total antibody levels against COVID-19 antigens by electrochemiluminescence assay. Out of 226 individuals, 129 were symptomatic and 97 were asymptomatic. Among the 129 symptomatic individuals, 74 exhibited an antibody response, whereas in the asymptomatic individuals, only 10 exhibited an antibody response. The antibody response was found to be significant in symptomatic individuals compared to that in asymptomatic individuals (p < 0.05). All follow-up individuals were seropositive at the end of both 6 and 8 months. Antibodies against SARS-CoV-2 persist for 8 months following infection. Despite the waning of antibodies against the nucleocapsid antigen, there was no complete disappearance of antibodies.

Retrospective Analysis of the Spread of SARS-CoV-2 in the Mediterranean Part of Bulgaria, During the First Wave of the Pandemic

“…20,21 An important part of controlling the spread of respiratory viruses is the availability of reliable diagnostic assays. The serological diagnosis of SARS-CoV-2 utilizes assays with different characteristics (antibody types and quantity), based on various principles, such as quick antigen tests based on nanoparticles, 29,30 qualitative and quantitative ELISA, immunofluorescence, [31][32][33] electrochemiluminescence assay 34 and automated systems. 35,36 Different serological tests also have different informativeness depending on the team and the combination of antibodies they prove.…”