The humoral immune response to SARS-CoV-2 is a benchmark for immunity and detailed
analysis is required to understand the manifestation and progression of COVID-19, monitor
seroconversion within the general population, and support vaccine development. The
majority of currently available commercial serological assays only quantify the SARS-CoV-2
antibody response against individual antigens, limiting our understanding of the immune
response. To overcome this, we have developed a multiplex immunoassay (MultiCoV-Ab)
including spike and nucleocapsid proteins of SARS-CoV-2 and the endemic human coronaviruses. Compared to three broadly used commercial in vitro diagnostic tests, our
MultiCoV-Ab achieves a higher sensitivity and specificity when analyzing a wellcharacterized sample set of SARS-CoV-2 infected and uninfected individuals. We find a
high response against endemic coronaviruses in our sample set, but no consistent crossreactive IgG response patterns against SARS-CoV-2. Here we show a robust, high-contentenabled, antigen-saving multiplex assay suited to both monitoring vaccination studies and
facilitating epidemiologic screenings for humoral immunity towards pandemic and endemic
coronaviruses.