ABSTRACT
IntroductionCoronavirus disease 2019 (COVID-19) and influenza share similar symptoms, which hampers diagnosis. Given that they require different containment and treatment strategies, fast and accurate distinction between the two infections is needed. This study evaluates the sensitivity and specificity of the LumiraDx SARS-CoV-2 & Flu A/B Test for simultaneous detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and influenza A/B from a single nasal swab. MethodsNasal samples were collected from patients as part of the ASPIRE (NCT04557046) and INSPIRE (NCT04288921) studies at point-of-care testing sites in the USA. ASPIRE study participants were included after developing COVID-19 symptoms in the last 14 days or following a positive SARS-CoV-2 test in the last 48 hours. INSPIRE study participants were included after developing influenza symptoms in the last 4 days. Samples were extracted into proprietary buffer and analysed using the LumiraDx SARS-CoV-2 & Flu A/B Test. A reference sample was taken from each subject, placed into universal transport medium and tested using reference SARS-CoV-2 and influenza reverse transcription polymerase chain reaction (RT-PCR) tests. The test and reference samples were compared using the positive percent agreement (PPA) and negative percent agreement (NPA), together with their 95% confidence intervals (CI). ResultsAnalysis of the data from the ASPIRE (N=124) and INSPIRE (N=159) studies revealed high levels of agreement between the LumiraDx SARS-CoV-2 & Flu A/B Test and the reference tests in detecting SARS-CoV-2 (PPA=95.5% [95% CI: 84.9%, 98.7%]; NPA=96.0% [95% CI: 90.9%, 98.3%]), influenza A (PPA=83.3% [95% CI: 66.4%, 92.7%]; NPA=97.7% [95% CI: 93.4%, 99.2%]) and influenza B (PPA=80.0% [95% CI: 62.7%, 90.5%]; NPA=95.3% [95% CI: 90.2%, 97.9%]). ConclusionsThe LumiraDx SARS-CoV-2 & Flu A/B Test shows a high agreement with the reference RT-PCR tests while simultaneously detecting and differentiating between SARS-CoV-2 and influenza A/B. Trial registration, ClinicalTrials.gov identifier: NCT04557046 and NCT04288921
ABSTRACT
IntroductionConcerns have been raised regarding the accuracy of diagnostic antigen testing for the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron variant. We compared the performance of the LumiraDx SARS-CoV-2 Antigen Test between symptomatic participants recruited prospectively during the Delta to Omicron variant transition in the USA. MethodsTwo paired anterior nasal swabs were collected from each participant (adults and children) within 12 days of symptom onset between November 24th, 2021 and February 1st, 2022, during which time Omicron replaced Delta as the dominant variant in the sample population. Swabs were tested by the LumiraDx SARS-CoV-2 Antigen Test and compared using real-time polymerase chain reaction (RT-PCR) reference testing. Reference samples identified as positive were sequenced to identify the SARS-CoV-2 variant. Positive percent agreement (PPA) was calculated, with results stratified by RT-PCR cycle threshold (Ct). ResultsOf the 38 participants for whom LumiraDx SARS-CoV-2 Antigen Test results were available, 36 were confirmed positive by RT-PCR. Overall, PPA of the LumiraDx SARS-CoV-2 Antigen Test was 94.7% (95% confidence interval: 82.3%, 99.4%) and PPA was 100% for samples with a Ct <33. Sufficient viral load for sequencing was present in nine samples (six Delta, three Omicron), all of which returned a positive result using the LumiraDx SARS-CoV-2 Antigen Test. There were no performance differences observed between participants with the Delta and Omicron variants. ConclusionsSARS-CoV-2 differences between Delta and Omicron variant mutations did not affect the performance of the LumiraDx SARS-CoV-2 Antigen Test which detects the nucleocapsid protein antigen. The LumiraDx SARS-CoV-2 Antigen Test can be a useful antigen test to diagnose emerging variants of coronavirus disease 2019.
