The SARS-CoV-2 outbreak has claimed millions of lives and caused significant clinical challenges. The availability of a rapid, cost-effective, and sensitive test to detect antibodies at different stages of COVID-19 is crucial for effective clinical management, epidemiological studies, and public health surveillance. Four novel peptides (SF1, SF2, SF4, SF6) and two multi-epitope fusion proteins (SFu1 and NSFu1) from less variable regions of the spike and nucleocapsid proteins were developed. After detailed in silico structural validation, all the proteins were expressed in E. coli (BL21), purified by Ni