Comparison of capillary blood and plasma samples for the evaluation of seroprevalence to SARS-CoV-2 antibodies by lateral flow immunoassay in a university population in Medellín, Colombia, 2020

OBJECTIVES: The aim of this study was to estimate the seroprevalence of anti-SARS-CoV-2 antibodies using the SARS-CoV-2 antibody test in a university population. Capillary blood and plasma samples were compared and correlated with symptomatology to establish rapid treatment processes and develop a public health strategy within the community. STUDY DESIGN: Descriptive study of seroprevalence of anti-SARS-CoV-2 antibodies in a university population. METHODS: Standardised and validated laboratory serological tests were used to assess the immune response detected in capillary blood and plasma samples. In this study, 280 participants from the University Colegio Mayor de Antioquia in the Municipality of Medellín, Colombia, were tested for SARS-CoV-2 antibodies in capillary blood and plasma samples between November 2020 and January 2021. RESULTS: In total, 29 (11.2%) individuals had positive results for anti-SARS-CoV-2 antibodies (IgG/IgM); 28 (96.6%) had positive results in plasma samples and 11 (37.9%) in capillary blood samples. The two tests were compared, and the overall sensitivity and specificity of capillary vs plasma samples was 36.7% and 99.6%, respectively. CONCLUSIONS: Anti-SARS-CoV-2 antibodies (IgG/IgM) can be used to estimate the seroprevalence in populations, including immunity by vaccination; however, capillary blood samples should not be used to detect previous infection as they provide low sensitivity compared to plasma samples.