Fig 1.
Distribution of nasopharyngeal samples positive for SARS-CoV-2.
Comparison of the Ct values between all positive samples (n= 720) and the positive samples selected for laboratory validation of RT-LAMP (n= 149). Mean ± SEM. Mann-Whitney U test (p > 0.05).
Fig 2.
Direct RT-LAMP in the PLUM, validation under laboratory conditions.
(A) ROC curve evaluating the PLUM’s performance for detecting SARS-CoV-2 by direct RT-LAMP. (B) Distribution of RT-LAMP TTRs against RT-qPCR Ct values for 137 positive (red dots) and 144 negative (blue dots) nasopharyngeal samples. RT-qPCR and RT-LAMP positives were defined by Ct < 35.0 and TTR ≤ 40.9’, respectively (dotted lines). (C) Distribution of RT-LAMP and RT-qPCR values for 117 positive and 144 negative nasopharyngeal samples with Ct values below 30. (D) Distribution of RT-LAMP and RT-qPCR values for 96 positive and 144 negative nasopharyngeal samples with Ct values below 25. (E) ROC curve evaluating the PLUM’s performance for detecting internal control (IC) by direct RT-LAMP. (F) Distribution of RT-LAMP TTRs for IC from 137 positive and 144 negative samples as determined by RT-qPCR for SARS-CoV-2. Mean ± SEM. Mann-Whitney U test (p > 0.05).
Table 1.
Diagnostic performance of SARS-CoV-2 detection by direct RT-LAMP assay in the PLUM using nasopharyngeal samples, laboratory validation.
Fig 3.
Direct RT-LAMP in the PLUM, validation under field conditions.
(A) Distribution of RT-LAMP TTRs against RT-qPCR Ct values for 23 positive (red dots) and 26 negative (blue dots) nasopharyngeal samples. RT-qPCR and RT-LAMP positives were defined by Ct < 35.0 and TTR ≤ 40.9’, respectively (dotted lines). (B) Distribution of RT-LAMP TTRs for IC from 23 positive and 26 negative samples as determined by RT-qPCR for SARS-CoV-2. Mean ± SEM. Mann-Whitney U test (p > 0.05).
Table 2.
ELISA performance statistics for serum IgG detection of spike-RBD and N antigens and seroprevalence.
Table 3.
Diagnostic performance of COVID-19 antibodies detection by ELISA assays in PLUM using sera samples, laboratory validation.
Fig 4.
Detection of COVID-19 antibodies in sera samples by ELISA assays in the PLUM device, validation under laboratory conditions.
(A) Distribution of spike-RBD ELISA absorbance (ABS) relative ratio as determined by a microplate reader against PLUM reading units (PRU) relative ratio from 643 positive (red dots) and 153 negative (blue dots) sera samples. (B) Distribution of N ELISA ABS relative ratio against PRU relative ratio from 272 positive and 528 negative sera samples. (C) Distribution of seroprevalence results from the average ABS from spike-RBD and N against the average PRU from the same antigens using 175 positive and 125 negative sera samples. Cohen’s kappa statistics are shown. Dashed lines represent the threshold determined by ROC curve analysis (Table 3).
Table 4.
Diagnostic performance of COVID-19 antibodies detection by ELISA assays in the PLUM using sera samples, field validation.
Fig 5.
Detection of COVID-19 antibodies in sera samples by ELISA assays in the PLUM device, validation under field conditions.
(A) Distribution of spike-RBD ELISA absorbance (ABS) relative ratio as determined by a microplate reader against PLUM reading units (PRU) relative ratio from 44 positive (red dots) and 18 negative (blue dots) sera samples. (B) Distribution of N ELISA ABS relative ratio against PRU relative ratio from 14 positive and 48 negative sera samples. (C) Distribution of seroprevalence results from the average ABS from spike-RBD and N against the average PRU from the same antigens using nine positive and 18 negative sera samples. Cohen’s kappa statistics are shown. Dashed lines represent the threshold determined by ROC curve analysis (Table 3).