Urgent Care Study of the LumiraDx SARS-CoV-2 Ag Test for Rapid Diagnosis of COVID-19
Abstract BackgroundTesting individuals suspected of SARS-CoV-2 infection is essential to reduce the spread of disease. The purpose of this study was to determine the false negativity rate of the LumiraDx SARS-CoV-2 Ag Test when utilized for testing individuals suspected of SARS-CoV-2 infection within 12 days of symptom onset. MethodsConcurrent swab samples were collected from patients suspected of SARS-CoV-2 infection by their healthcare provider within two different urgent care centers. One swab was tested using the LumiraDx SARS-CoV-2 Ag Test. Negative results in patients considered at moderate to high risk of SARS-CoV-2 infection were confirmed at a regional reference laboratory by PCR using the additional swab sample. ResultsFrom October 19, 2020 – January 3, 2021, a total of 2241 tests were performed using the LumiraDx SARS-CoV-2 Ag Test, with 549 (24.5%) testing positive and 1692 (75.5%) testing negative. A subset (800) of the samples rendering a negative LumiraDx SARS-CoV-2 Ag Test were also tested using a PCR-based test for SARS-CoV-2. Of this subset, 770 (96.3%) tested negative, and 30 (3.8%) tested positive. A cycle threshold (CT) was available for 17 of the 30 specimens that yielded discordant results, with an average CT value of 31.2, an SD of 3.0, and a range of 25.2–36.3. CT was >30.0 in 11/17 specimens (64.7%). ConclusionsThis study demonstrates that negative results obtained with the LumiraDx SARS-CoV-2 Ag Test had 96.3% agreement with PCR-based SARS-CoV-2 tests, with a low false negative rate of 3.8% when used in a community-based setting.