AH971 and AV865 antibodies label the SARS-CoV-2 nucleocapsid protein in focus-forming assay

AH971 and AV865 antibodies detect the nucleocapsid proteins of severe acute respiratory SARS coronavirus-2 (SARS-CoV-2) in a focus forming assay

Analytical performance of eleven SARS-CoV-2 antigen-detecting rapid tests for Delta variant

AbstractGlobal concerns arose as the emerged and rapidly spreading SARS-CoV-2 Delta variant. To date, few data on routine diagnostic performance for Delta are available. Here, we investigate the analytical performance of eleven commercially available antigen-detecting rapid diagnostic tests (Ag-RDTs) for Delta VOC in comparison with current and earlier VOCs (Alpha, Beta and Gamma) and early pandemic variant using cultured SARS-CoV-2. Comparable sensitivity was observed for Delta for the majority of Ag-RDTs.</jats:p

Analytical comparison of nine SARS-CoV-2 antigen-detecting rapid diagnostic tests for emerging SARS-CoV-2 variants

AbstractSeveral SARS-CoV-2 variants of concern/interest (VOC/VOI) emerged recently, with VOCs outcompeting earlier lineages on a global scale. To date, few data on routine diagnostic performance for VOC/VOIs are available. Here, we investigate the analytical performance of nine commercially available antigen-detecting rapid diagnostic tests (Ag-RDTs) for VOC B.1.1.7, B.1.351, P.1 and VOI P.2 with cultured SARS-CoV-2. Comparable or higher sensitivity was observed for VOC/VOI compared to a non-VOC/VOI early-pandemic virus for all Ag-RDTs.</jats:p

Infectious viral load in unvaccinated and vaccinated patients infected with SARS-CoV-2 WT, Delta and Omicron

AbstractBackgroundViral load (VL) is one determinant of secondary transmission of SARS-CoV-2. Emergence of variants of concerns (VOC) Alpha and Delta was ascribed, at least partly, to higher VL. Furthermore, with parts of the population vaccinated, knowledge on VL in vaccine-breakthrough infections is crucial. As RNA VL is only a weak proxy for infectiousness, studies on infectious virus presence by cell culture isolation are of importance.MethodsWe assessed nasopharyngeal swabs of COVID-19 patients for quantitative infectious viral titres (IVT) by focus-forming assay and compared to overall virus isolation success and RNA genome copies. We assessed IVTs during the first 5 symptomatic days in a total of 384 patients: unvaccinated individuals infected with pre-VOC SARS-CoV-2 (n= 118) or Delta (n= 127) and vaccine breakthrough infections with Delta (n= 121) or Omicron (n=18).FindingsCorrelation between RNA copy number and IVT was low for all groups. No correlation between IVTs and age or sex was seen. We observed higher RNA genome copies in pre-VOC SARS-CoV-2 compared to Delta, but significantly higher IVTs in Delta infected individuals. Vaccinated Delta infected individuals had significantly lower RNA genome copies and IVTs compared to unvaccinated subjects and cleared virus faster. In addition, vaccinated individuals with Omicron infection had comparable IVTs to Delta breakthrough infections.InterpretationQuantitative IVTs can give detailed insights into virus shedding kinetics. Vaccination was associated with lower infectious titres and faster clearance for Delta, showing that vaccination would also lower transmission risk. Omicron vaccine-breakthrough infections did not show elevated IVTs compared to Delta, suggesting that other mechanisms than increase VL contribute to the high infectiousness of Omicron.FundingThis work was supported by the Swiss National Science Foundation 196644, 196383, NRP (National Research Program) 78 Covid-19 Grant 198412, the Fondation Ancrage Bienfaisance du Groupe Pictet and the Fondation Privée des Hôpitaux Universitaires de Genève.</jats:sec

Infectious viral load in unvaccinated and vaccinated patients infected with SARS-CoV-2 WT, Delta and Omicron

Abstract Viral load (VL) is one determinant of secondary transmission of SARS-CoV-2. Emergence of variants of concerns (VOC) Alpha and Delta was ascribed, at least partly, to higher VL. Furthermore, with parts of the population vaccinated, knowledge on VL in vaccine-breakthrough infections is crucial. As RNA VL is only a weak proxy for infectiousness, studies on infectious virus presence by cell culture isolation are of importance. We assessed nasopharyngeal swabs of COVID-19 patients for quantitative infectious viral titres (IVT) by focus-forming assay and compared to overall virus isolation success and RNA genome copies. We assessed IVTs during the first 5 symptomatic days in a total of 440 patients: unvaccinated individuals infected with pre-VOC SARS-CoV-2 (n= 118) or Delta (n= 127) and vaccine-breakthrough infections with Delta (n= 133) or Omicron (n=62). Correlation between RNA copy number and IVT was low for all groups. No correlation between IVTs and age or sex was seen. We observed higher RNA genome copies in pre-VOC SARS-CoV-2 compared to Delta, but significantly higher IVTs in Delta infected individuals. Vaccinated Delta infected individuals had significantly lower RNA genome copies and IVTs compared to unvaccinated subjects and cleared virus faster. In addition, vaccinated individuals with Omicron infection had lower IVTs in comparison to Delta breakthrough infections. Quantitative IVTs can give detailed insights into virus shedding kinetics. Vaccination was associated with lower infectious titres and faster clearance for Delta, showing that vaccination would also lower transmission risk. Omicron vaccine-breakthrough infections did not show elevated IVTs compared to Delta, suggesting that other mechanisms than increased VL contribute to the high infectiousness of Omicron.</jats:p