Urgent care study of the LumiraDx SARS-CoV-2 Ag Test for rapid diagnosis of COVID-19

Jared Gresh,Brian Duchateau,Harold Kisner

doi:10.1186/s41512-021-00113-7

Abstract

BackgroundTesting individuals suspected of severe acute respiratory syndrome–like coronavirus 2 (SARS-CoV-2) infection is essential to reduce the spread of disease. The purpose of this retrospective 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.MethodsConcurrent swab samples were collected from patients suspected of SARS-CoV-2 infection by their healthcare provider within two different urgent care centers located in Easton, MA, USA and East Bridgewater, MA, USA. 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 polymerase chain reaction (PCR) using the additional swab sample. The data included in this study was collected retrospectively as an analysis of routine clinical practice.ResultsFrom October 19, 2020 to 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 was 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. Negative results obtained with the LumiraDx SARS-CoV-2 Ag test demonstrated 96.3% agreement with PCR-based tests (CI 95%, 94.7–97.4%). 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 the LumiraDx SARS-CoV-2 Ag Test had a low false-negative rate of 3.8% when used in a community-based setting.

Highlights

Testing individuals suspected of severe acute respiratory syndrome–like coronavirus 2 (SARS-CoV-2) infection is essential to reduce the spread of disease
From October 19, 2020 to January 3, 2021, all symptomatic patients presenting within 12 days of symptom onset, at two different urgent care centers (East Bridgewater, MA or Easton, MA), within a community medical center setting were tested with the LumiraDx SARS-CoV-2 Ag Test
During the initial clinical and risk assessment of the patients, 800 (47.3%) of the patients rendering a negative LumiraDx SARS-CoV-2 Ag Test result were determined to have moderate to high likelihood of SARS-CoV-2 infection, and were tested using a polymerase chain reaction (PCR)-based test for SARS-CoV-2 (Table 2)

Summary

Introduction

Testing individuals suspected of severe acute respiratory syndrome–like coronavirus 2 (SARS-CoV-2) infection is essential to reduce the spread of disease. As of June 2021, 28 different EUA-labeled rapid tests that identify the presence of SARS-CoV-2 antigen are available on the US market, most of which are performed at the point of care with results being available in less than 30 min with some tests requiring only 15 min or less to render a result [4]. Rapid SARS-CoV-2 antigen tests can provide a result before the patient even leaves the medical institution at which the test has been administered. Providing a rapid result to identify SARS-CoV-2–infected individuals can help to prevent and truncate the spread of disease [5,6,7]

Methods

Results

Discussion

Conclusion