Performance evaluation of a rapid point-of-care microfluidic immunofluorescence assay for the detection of SARS-CoV-2 antibodies

The LumiraDx SARS-CoV-2 Antibody (Ab) Test is a point-of-care (POC) test that uses a rapid, high sensitivity microfluidic immunofluorescence assay to qualitatively detect total antibodies to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The test was evaluated for clinical agreement using samples with real-time polymerase chain reaction (RT-PCR)-confirmed SARS-CoV-2 infection status across POC settings.

Methods

Plasma samples from participants (≥18 years) were collected from clinical studies and commercial suppliers for positive and negative agreement analysis. Matrix equivalency was determined using donor whole blood, plasma and serum samples spiked with immunoglobulin (Ig) M and IgG. Cross-reactivity was analysed using samples with known related and high-prevalence pathogens. Fingerstick application with capillary blood (applied directly or using transfer tube) from participants (≥18 years) was analysed following RT-PCR testing. Application was performed by untrained users and ease of use of the LumiraDx SARS-CoV-2 Ab Test was investigated.

Results

An overall positive agreement of 97.2% (95% confidence interval [CI]: 90.4, 99.2%; n=72) was determined in samples obtained ≤118 days following RT-PCR testing, and 100% (n=55) in a subset obtained >7 days following RT-PCR testing. Samples from participants without a history of SARS-CoV-2 infection (endemic symptomatic, asymptomatic and non-endemic participants) showed an overall negative agreement of 100% (95% CI: 98.7, 100%; n=290) with RT-PCR testing. Matrix demonstrated 100% agreement and no cross-reactivity with any of the tested pathogens; 100% agreement was observed between capillary fingerstick application and RT-PCR results, as well as between sample application methods. Test operators indicated that the LumiraDx SARS-CoV-2 Ab Test was easy to use.

Conclusion

The LumiraDx SARS-CoV-2 Ab Test demonstrated excellent agreement when compared with RT-PCR test results, using capillary and venous whole blood, plasma and serum. This study reported 97.2% positive and 100% negative agreement overall in samples collected aer RT-PCR testing, and 100% positive agreement in samples obtained at least 7 days after RT-PCR confirmation when using the LumiraDx SARS-CoV-2 Ab Test.

The data represented in this document is only applicable to the LumiraDx SARS-CoV-2 Ab Test that has been authorized by FDA under an EUA.

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This product has not been FDA cleared or approved but has been authorized for emergency use by FDA under an EUA for use by authorized laboratories.
Testing of fingerstick whole blood specimens is limited to laboratories certified under the Clinical Laboratory Improvement Amendments of 1988 (CLIA), 42 U.S.C. §263a, that meet requirements to perform moderate, high or waived complexity tests. Testing of fingerstick whole blood is authorized for use at the Point of Care (POC), i.e., in patient care settings operating under a CLIA Certificate of Waiver, Certificate of Compliance, or Certificate of Accreditation.
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