TITLE:
Multiplex IgG Reactivity to SARS-CoV-2 Antigens in Senegal
AUTHORS:
Moussa Ndour, Moustapha Mbow, Biscotine F. Makoutchouang Nzonde, Joséphine K. Badiane, Marouba Cisse, Matar Gningue, Ibrahima Diallo, Abdou Aziz Diallo, Mady Ndiaye, Massamba Sylla, Babacar Mbengue, Souleymane Mboup, Tandakha N. Dieye
KEYWORDS:
SARS-CoV-2, COVID-19, Multiplex Serology, IgG, Nucleocapsid, Spike, Senegal, Pre-Pandemic Cross-Reactivity
JOURNAL NAME:
Open Journal of Immunology,
Vol.16 No.4,
October
27,
2026
ABSTRACT: Background: Multiplex serology can distinguish antibody reactivity to several viral targets, but its interpretation in African populations requires attention to the timing of sampling and pre-pandemic cross-reactivity. This study aimed to describe IgG reactivity to five SARS-CoV-2 antigens in three Senegalese groups. Methodology: In this retrospective study, 380 archived plasma samples were tested using the CoViDiag® multiplex immunoassay: 162 collected before the pandemic, 162 from participants with RT-PCR-confirmed SARS-CoV-2 infection, and 56 from occupationally exposed healthcare workers. The assay simultaneously assessed IgG antibodies against nucleocapsid (N), spike S1, spike S2, the receptor-binding domain (RBD), and the N-terminal domain (NTD). Proportions are presented with Wilson 95% confidence intervals (CIs). Results: Overall CoViDiag positivity differed among groups (P Conclusion: Multiplex testing revealed heterogeneous IgG profiles dominated by N reactivity. The observed positive agreement with RT-PCR cannot be interpreted as an estimate of the assay’s intrinsic sensitivity because the interval between infection and blood collection was unavailable. Pre-pandemic signals support cautious interpretation of serosurveys and do not demonstrate protective immunity.