The detection of antibody responses using serological tests provides means to diagnose infections, follow disease transmission, and monitor vaccination responses. The coronavirus disease 2019 (COVID-19) pandemic, caused by the SARS-CoV-2 virus, highlighted the need for rapid development of robust and reliable serological tests to follow disease spreading. Moreover, the rise of SARS-CoV-2 variants emphasized the need to monitor their transmission and prevalence in the population. For this reason, multiplex and flexible serological assays are needed to allow for rapid inclusion of antigens representing new variants as soon as they appear. In this chapter, we describe the generation and application of a multiplex serological test, based on bead array technology, to detect anti-SARS-CoV-2 antibodies in a high-throughput manner, using only a few microliters of sample. This method is currently expanding to include a multi-disease antigen panel that will allow parallel detection of antibodies towards several infectious agents.