: Immunoassay-based serology techniques play key roles in many SARS-CoV-2 research programs due to their ability to identify and characterize the immune response of individuals already infected by the virus through analysis of biomarkers such as immunoglobulins (Ig). However, the limited sensitivity and resolution offered by traditional assay platforms and their serology assays can leave unanswered crucial research questions. We harnessed the power of the Single Molecule Counting (SMC™) ultrasensitive immunoassay platform for the development of new products to address the scientific community’s needs including identifying low level SARS-CoV-2 mediated antibody response and resolving subtle differences in humoral immunity among individuals. The new SMC™ SARS-CoV-2 RBD IgG kit can be used by researchers to accurately understand the extent of SARS-CoV-2 infection in society, thoroughly profile immune responses after vaccine challenge, and understand heterogeneous responses to infection among individuals and subpopulations.’