Detection of The Virus and Antibodies of SARS-Cov-2 from Healthy Indonesian Volunteers In 2020: Analysis Using Qualitative and Quantitative Methods

Abstract

Individuals with COVID-19 and no symptoms, known as asymptomatic carriers, are found mostly in the community. Testing is very important to help reduce the spread of COVID-19. This study aimed to detect virus and antibodies of SARSCoV-2 in healthy Indonesian volunteers. In September 2020, 45 healthy volunteers participated were taken nasopharyngeal/ oropharyngeal swabs to detect the virus SARS-CoV-2 using RT-PCR, and blood samples to detect antibodies qualitatively by three rapid tests (Vazyme, Clugene, and RIGHA kits) and quantitatively by ELISA tests. Among healthy volunteers, COVID-19 asymptomatic carriers who have RT-PCR positive were 16% (7/45) with average of Ct 36.14. The seroprevalence of total SARS-CoV-2 antibodies (IgM and/or IgG) in RT-PCR positivity (asymptomatic carriers) detected by vazyme, clugene and RIGHA kits was 86%, 76% and 52%, respectively and was higher than the negative group (34, 21 and 24%). SARS-CoV-2 IgG antibody titers in the group that were positive for IgM and/or IgG (detected in at least one rapid test) by ELISA was averaged 109.76 ± 114.14 BAU/ml and significantly higher in negative group with titer of 11.45 ± 9.87 BAU/ ml. High titer of SARS-CoV-2 IgG anti-RBD antibodies was resulted in consistent positive in three rapid tests (vazyme, clugene, and RIGHA) compared to lower titer. Our findings suggest that healthy individuals with virus and/or antibodies of SARS-CoV-2 may have been infected recently or in the past. Antibody-positive results detected in healthy volunteers by three rapid tests were more common in asymptomatic carriers, and had higher titer antibody