There is an ongoing need of developing sensitive and specific methods for the determination of SARS-CoV-2 seroconversion . For this purpose, we have developed a multiplexed flow cytometric bead array (C19BA) that allows the identification of IgG and IgM antibodies against three immunogenic proteins simultaneously: the spike receptor-binding domain (RBD), the spike protein subunit 1 (S1) and the nucleoprotein (N). Using different cohorts of samples collected before and after the pandemic, we show that this assay is more sensitive than ELISAs performed in our laboratory . The combination of three viral antigens allows for the interrogation of full seroconversion . Importantly, we have detected N-reactive antibodies in COVID-19-negative individuals . Here we present an immunoassay that can be easily implemented and has superior potential to detect low antibody titers compared to current gold standard serology methods.