Fig 1.
Positive predictive values (PPV) and negative predictive values (NPV) by prevalence for each commercial and in-house assay on dried blood spot specimens.
PPV and NPV is presented for n = 10 SARS-CoV-2 antibody negative DBS specimens and n = 10 SARS-CoV-2 antibody positive DBS specimens. One 6 mm (1/4 inch) punch was used for the EUROIMMUN assay and two 6 mm (1/4 inch) punches were used for the Platelia and in-house assays. Data from four 6 mm (1/4 inch) punches is presented for all other assays. EUROIMMUN = Anti-SARS-CoV-2 ELISA assay (EUROIMMUN, Lübeck, Germany). Platelia = SARS-CoV-2 assay (Bio-Rad, Hercules, California). LIASON = SARS-CoV-2 assay (DiaSorin, Saluggia, Italy). COV2G = SARS-CoV-2 COV2G assay (Siemens, Erlangen, Germany). COV2T = SARS-CoV-2 COV2T assay (Siemens). Elecsys S = Quantitative Anti-SARS-CoV-2 assay (Elecsys spike; Roche, Basel, Switzerland). Elecsys N = Anti-SARS-CoV-2 assay (Elecsys nucleocapsid; Roche). VITROS = Anti-SARS-CoV-2 assay (Ortho Clinical Diagnostics, Raritan, New Jersey). Architect = SARS-CoV-2 assay (Abbott, Mississauga, Canada). GSP/DELFIA = Anti-SARS-CoV-2 assay (PerkinElmer, Waltham, Massachusetts). In-house S (U of T) = In-house spike assay (University of Toronto). In-house RBD (U of T) = In-house RBD assay (University of Toronto). In-house N (U of T) = In-house nucleocapsid assay (University of Toronto). In-house S, mono (U of O) = In-house monoclonal spike assay (University of Ottawa). In-house RBD, mono (U of O) = In-house monoclonal RBD assay (University of Ottawa). In-house N, mono (U of O) = In-house monoclonal nucleocapsid assay (University of Ottawa). The VITROS assay could not achieve a specificity greater than 0% therefore, only PPV is shown.
Fig 2.
Inter-assay concordance (A) and Cohen’s kappa coefficient (B) for SARS-CoV-2 antibody testing on dried blood spot specimens. Concordance (%) and Cohen’s kappa coefficient are presented for n = 10 SARS-CoV-2 antibody negative DBS specimens and n = 10 SARS-CoV-2 antibody positive DBS specimens. One 6 mm (1/4 inch) punch was used for the EUROIMMUN assay and two 6 mm (1/4 inch) punches were used for the Platelia and in-house assays. EUROIMMUN = Anti-SARS-CoV-2 ELISA assay (EUROIMMUN, Lübeck, Germany). Platelia = SARS-CoV-2 assay (Bio-Rad, Hercules, California). LIASON = SARS-CoV-2 assay (DiaSorin, Saluggia, Italy). COV2G = SARS-CoV-2 COV2G assay (Siemens, Erlangen, Germany). COV2T = SARS-CoV-2 COV2T assay (Siemens). Elecsys S = Quantitative Anti-SARS-CoV-2 assay (Elecsys spike; Roche, Basel, Switzerland). Elecsys N = Anti-SARS-CoV-2 assay (Elecsys nucleocapsid; Roche). VITROS = Anti-SARS-CoV-2 assay (Ortho Clinical Diagnostics, Raritan, New Jersey). Architect = SARS-CoV-2 assay (Abbott, Mississauga, Canada). GSP/DELFIA = Anti-SARS-CoV-2 assay (PerkinElmer, Waltham, Massachusetts). In-house S (U of T) = In-house spike assay (University of Toronto). In-house RBD (U of T) = In-house RBD assay (University of Toronto). In-house N (U of T) = In-house nucleocapsid assay (University of Toronto). In-house S, mono (U of O) = In- house monoclonal spike assay (University of Ottawa). In-house RBD, mono (U of O) = In-house monoclonal RBD assay (University of Ottawa). In-house N, mono (U of O) = In-house monoclonal nucleocapsid assay (University of Ottawa).
Table 1.
Assay performance for SARS-CoV-2 antibody testing on dried blood spot specimens (DBS).
Fig 3.
Receiver operating characteristic (ROC) curve for each commercial and in-house assay on dried blood spot specimens.
ROC curves are presented for n = 10 SARS-CoV-2 antibody negative DBS specimens and n = 10 SARS-CoV-2 antibody positive DBS specimens. One 6 mm (1/4 inch) punch was used for the EUROIMMUN assay and two 6 mm (1/4 inch) punches were used for the Platelia and in-house assays. Data from four 6 mm (1/4 inch) punches is presented for all other assays. EUROIMMUN = Anti-SARS-CoV-2 ELISA assay (EUROIMMUN, Lübeck, Germany). Platelia = SARS-CoV-2 assay (Bio-Rad, Hercules, California). LIASON = SARS-CoV-2 assay (DiaSorin, Saluggia, Italy). COV2G = SARS-CoV-2 COV2G assay (Siemens, Erlangen, Germany). COV2T = SARS-CoV-2 COV2T assay (Siemens). Elecsys S = Quantitative Anti-SARS-CoV-2 assay (Elecsys spike; Roche, Basel, Switzerland). Elecsys N = Anti-SARS-CoV-2 assay (Elecsys nucleocapsid; Roche). VITROS = Anti-SARS-CoV-2 assay (Ortho Clinical Diagnostics, Raritan, New Jersey). Architect = SARS-CoV-2 assay (Abbott, Mississauga, Canada). GSP/DELFIA = Anti-SARS-CoV-2 assay (PerkinElmer, Waltham, Massachusetts). In-house S (U of T) = In-house spike assay (University of Toronto). In-house RBD (U of T) = In-house RBD assay (University of Toronto). In-house N (U of T) = In-house nucleocapsid assay (University of Toronto). In-house S, mono (U of O) = In-house monoclonal spike assay (University of Ottawa). In-house RBD, mono (U of O) = In-house monoclonal RBD assay (University of Ottawa). In-house N, mono (U of O) = In-house monoclonal nucleocapsid assay (University of Ottawa).
Fig 4.
Distribution of values obtained for each commercial and in-house assay on dried blood spot (DBS) specimens.
Each panel shows the optical density ratio (OD Ratio), arbitrary units per mL (AU/mL), index, units per mL (U/mL), cut-off index, or signal to cut-off ratio (S/Co) for SARS-CoV-2 antibody negative DBS specimens (n = 10) represented in blue and SARS-CoV-2 antibody positive DBS specimens (n = 10) represented in orange. All values are log10 transformed to aid with visualisation. One 6 mm (1/4 inch) punch was used for the EUROIMMUN assay and two 6 mm (1/4 inch) punches were used for the Platelia and in-house assays. Data from four 6 mm (1/4 inch) punches is presented for all other assays. EUROIMMUN = Anti-SARS-CoV-2 ELISA assay (EUROIMMUN, Lübeck, Germany). Platelia = SARS-CoV-2 assay (Bio-Rad, Hercules, California). LIASON = SARS-CoV-2 assay (DiaSorin, Saluggia, Italy). COV2G = SARS-CoV-2 COV2G assay (Siemens, Erlangen, Germany). COV2T = SARS-CoV-2 COV2T assay (Siemens). Elecsys S = Quantitative Anti-SARS-CoV-2 assay (Elecsys spike; Roche, Basel, Switzerland). Elecsys N = Anti-SARS-CoV-2 assay (Elecsys nucleocapsid; Roche). VITROS = Anti-SARS-CoV-2 assay (Ortho Clinical Diagnostics, Raritan, New Jersey). Architect = SARS-CoV-2 assay (Abbott, Mississauga, Canada). GSP/DELFIA = Anti-SARS-CoV-2 assay (PerkinElmer, Waltham, Massachusetts). In-house S (U of T) = In-house spike assay (University of Toronto). In-house RBD (U of T) = In-house RBD assay (University of Toronto). In-house N (U of T) = In-house nucleocapsid assay (University of Toronto). In-house S, mono (U of O) = In-house monoclonal spike assay (University of Ottawa). In-house RBD, mono (U of O) = In-house monoclonal RBD assay (University of Ottawa). In-house N, mono (U of O) = In-house monoclonal nucleocapsid assay (University of Ottawa).
Table 2.
Area under the receiver operating characteristic curve (AUC) for each commercial and in-house assay on dried blood spot specimens (DBS).
Table 3.
SARS-CoV-2 antibody positive and negative plasma used to contrive dried blood spot specimens.
Table 4.
Commercial and in-house serological tests assessed for SARS-CoV-2 antibody testing on dried blood spot specimens.