Evaluation of the diagnostic performance of iChroma serological test in high SARS-CoV-2 seroprevalence setting in Gabon

Coronavirus disease 2019 (COVID-19) has been a major global health concern over the past few years. The African region has remained less affected in terms of mortality, however, estimating the true cumulative incidence in this region is challenging due to several limitations. Serological tests can help evaluate the SARS-CoV-2 exposure at both individual and population levels. Several serological rapid tests have been developed, but their performance at population level is not always known. This current study aimed to evaluate the diagnostic performance of the iChroma test for the rapid detection of SARS-CoV-2 antibodies. Participants included in this study were recruited during the national seroprevalence household survey. The WANTAI SARS-CoV-2 Ab Enzyme-Linked Immunosorbent Assay (ELISA), was used as reference test. All samples were evaluated using both WANTAI ELISA and iChroma. In addition, a well-characterised SARS-CoV-2 rapid test (SARS-CoV-2 rapid antibody test 2.0, Roche) was evaluated on a reduced number of sample as control for rapid test using Cobas instrument. A total of 1128 samples were analysed in this study. Of the study participants, 51,2% were women with a mean age of 36 (SD: 16). Overall, 91,6% of participants had a positive WANTAI SARS-CoV-2 Ab ELISA results. In this high-seroprevalence setting, the iChroma test showed a poor agreement with the ELISA test, with a kappa value of 28 (19–38). This rapid test demonstrated a good sensitivity but a poor specificity in this setting. In contrast, we found an excellent agreement between the Roche SARS-CoV-2 rapid antibody test 2.0. and WANTAI SARS-CoV-2 Ab ELISA with a kappa value of 92% (86–98%). In this high seroprevalence setting, the specificity of iChroma test was significantly reduced and showed poorly correlation with the ELISA results. This rapid test has never been evaluated in a large scale population setting. As previously shown in other studies, Roche showed a good diagnostic performance in correlation with ELISA. The current results revealed the poor specificity of iChroma test in high SARS-CoV-2 seroprevalence settings. No applicable.