A promising target for both diagnosis and therapeutics treatments of the new disease named COVID-19 is the coronavirus (CoV) spike (S) glycoprotein. The spike protein, which is responsible for the "corona" (Latin word for crown) appearance in all coronaviruses, is a type I glycoprotein that has an especial role in the interaction between the virus and the host cell. This protein attaches itself to specific cellular receptors and suffers a conformational change that enables the fusion of the virus and the cell. Studies have shown that the SARS-CoV-2's S RBD protein interacts strongly with the Angiotensin-converting enzyme 2 (ACE2). S-RBD protein in order to enlighten the binding epitopes of these Abs. Because of the conservation of S-RBD protein sequence and its strong immunogenicity, the S-RBD protein of coronavirus is chosen as a diagnostic tool. COVID-19 antibodies can be produced by a host immune system following exposure to SARS-CoV-2. IgM antibodies are also known as immunoglobulins IgG and IgM, respectively, and are among the antibody isotypes produced by vertebrate immune systems.The ELISA microplate is coated with the SARS-CoV-2 S-RBD protein. The coated S-RBD protein binds with COVID-19 IgM S-RBD antibodies in the serum sample.