RESUMO
Measurement of quantitative antibody responses are increasingly important in evaluating the immune response to infection and vaccination. In this study we describe the validation of a quantitative, multiplex serologic assay utilising an electrochemiluminescence platform, which measures IgG against the receptor binding domain (RBD), spike S1 and S2 subunits and nucleocapsid antigens of SARS-CoV-2. The assay displayed a sensitivity ranging from 73-91% and specificity from 90 to 96% in detecting previous infection with SARS-CoV-2 depending on antigenic target and time since infection, and this assay highly correlated with commercially available assays. The within-plate coefficient of variation ranged from 3.8-3.9% and the inter-plate coefficient of variation from 11-13% for each antigen.
RESUMO
BackgroundThe COVID-19 pandemic has caused huge pressure on healthcare systems worldwide. Public health measures to control the virus are reliant on testing, including appropriate collection of specimens for analysis. MethodsA prospective study of nasopharyngeal swab technique by staff in an academic tertiary referral centre was carried out. Nasopharyngeal swab technique was evaluated by a novel design of a navigated swab on a three-dimensional model head. ResultsSwab technique of 228 participants was assessed. Technique was poor, with a success rate of nasopharyngeal swabbing at 38.6%. Angle and length of insertion were significantly different between those with successful and unsuccessful technique. Doctors were significantly more accurate than nurses and non-healthcare professionals (p<0.01). ConclusionInaccurate specimen collection from poor swab technique could contribute to a false negative rate of testing for SARS-CoV-2. Specific training in nasopharyngeal anatomy and swab technique may improve the accuracy of nasopharyngeal swabbing.
