Pre-vaccination immune response to COVID-19 in a population in Northeast Portugal.

Purpose: To study the immunization status and IgM and IgG antibody behavior against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in an unvaccinated population of Northeast Portugal (including RT-PCR diagnosed and undiagnosed individuals).

Methods: Application of a clinical-epidemiological survey, and analysis of IgM and IgG SARS-COV-2 antibodies (against N core protein) in 362 participants that voluntarily sought the laboratory for testing.

Results: At the time of the analysis, 31.