Qualitative enzyme-linked immunosorbent assay of specific IgA antibodies against Covid-19 based on the ELISA technique. The 96-well ELISA plates are coated with the recombinant specific antigen (Mpro or also called 3CLpro) to bind the antibodies present in human serum and plasma samples (K2-EDTA, K3-EDTA, Heparin-Li, Sodium Citrate). The intended use of the assay is to assist in the identification of individuals with an adaptive immune response to SARS-CoV-2, indicating a previous or recent infection and contributing in combination with other tests (PCR or antigen), to the determination of the stage of infection. Additionally, this assay can be used in research, seroprevalence studies and epidemiological surveillance.