Performance and Operational Evaluation of the Access Bio CareStart Rapid Antigen Test in a High-Throughput Drive-Through Community Testing Site in Massachusetts

Abstract

Background To facilitate deployment of point-of-care testing for SARS-CoV-2, we evaluated the Access Bio CareStart COVID-19 Antigen test in a high-throughput, drive-through, free community testing site using anterior nasal (AN) swab RT-PCR for clinical testing. Methods Consenting symptomatic and asymptomatic children (≤18 years) and adults received dual AN swabs. CareStart testing was performed with temperature/humidity monitoring. All tests had two independent reads to assess inter-operator agreement. Patients with positive CareStart results were called and instructed to isolate pending RT-PCR results. The paired RT-PCR result was the reference for sensitivity and specificity calculations. Results Of 1603 participants, 1245 adults and 253 children had paired RT-PCR/CareStart results and complete symptom data. 83% of adults and 87% of children were asymptomatic. CareStart sensitivity/specificity were 84.8% (95% confidence interval [CI] 71.1-93.7)/97.2% (92.0-99.4) and 85.7% (42.1-99.6)/89.5% (66.9-98.7) in adults and children, respectively, within 5 days of symptoms. Sensitivity/specificity were 50.0% (41.0-59.0)/99.1% (98.3-99.6) in asymptomatic adults and 51.4% (34.4-68.1)/97.8% (94.5-99.4) in asymptomatic children. Sensitivity in all 234 RT-PCR-positive people was 96.3% with cycle threshold (Ct) ≤25, 79.6% with Ct ≤30, and 61.4% with Ct ≤35. All 21 false positive CareStart tests had faint but normal bands. Inter-operator agreement was 99.5%. Operational challenges included identification of faint test bands and inconsistent swab elution volumes. Conclusions CareStart had high sensitivity in people with Ct ≤25 and moderate sensitivity in symptomatic people overall. Specificity was unexpectedly lower in symptomatic versus asymptomatic people. Excellent inter-operator agreement was observed, but operational challenges indicate that operator training is warranted.

Diagnostic Accuracy of SARS-CoV-2 Antigen Tests for Community Transmission Screening: A Systematic Review and Meta-Analysis

“…The supplementary information presents the sensitivities and specificities of antigen tests for SARS-CoV-2 from the included studies (see Figure S1). [16,18,22,23,[28][29][30]33]. The meta-analysis produced a pooled sensitivity of 0.76 (95% CI: 0.58-0.88) and a pooled specificity of 1.00 (95% CI: 0.99-1.00).…”

“…Eighteen studies with 34,865 participants were retrieved [16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33]. Figure 1 depicts the process of the literature search, and Table 1 presents detailed characteristics of the studies.…”

“…Figure 1 depicts the process of the literature search, and Table 1 presents detailed characteristics of the studies. All studies in the meta-analysis used a prospective study design, and five studies enrolled participants in the drive-through testing sites [16,19,26,28,31]. Eight studies evaluated the diagnostic performance of antigen tests with nasal swab specimens [16,18,22,23,[28][29][30]33], six assessed the accuracy of antigen tests with nasopharyngeal swab specimens [21,[24][25][26][27]31], seven provided cycle threshold (Ct) values of positive RT-PCR tests [24,25,[28][29][30][31][32], and eight reported cutoff values of Ct [16,[21][22][23]25,27,28,33].…”

“…The meta-analysis for antigen tests generated a pooled sensitivity of 0.82 (95% CI: 0.71-0.89) and a pooled specificity of 1.00 (95% CI: 0.99-1.00) (Figure 2). Eight studies with 16,470 patients discussed the accuracy of antigen tests using nasal swab specimens [16,18,22,23,[28][29][30]33]. The meta-analysis produced a pooled sensitivity of 0.76 (95% CI: 0.58-0.88) and a pooled specificity of 1.00 (95% CI: 0.99-1.00).…”

Comparative analyses of FDA EUA-approved rapid antigen tests and RT-PCR for COVID-19 quarantine and surveillance-based isolation

“…Improper sampling and analysis of samples of these RA tests can influence the rate of false-positives and false-negatives 52,53 , and would therefore impact the required quarantine duration and testing frequency. Independently evaluated datasets on the testing of COVID-19 infections in the community were available for three of the RA tests 37,54 , enabling a comparison to the datasets that were provided from the EUA documentation. In two of the three comparisons (Sofia and CareStart), diagnostic sensitivity in independent analyses was lower than in ideal conditions.…”