Current best evidence for clinical care (more info)
(1) Background: The detection of SARS-CoV-2 RNA in nasopharyngeal samples through real-time reverse transcription-polymerase chain reaction (RT-PCR) is considered the standard gold method for the diagnosis of SARS-CoV-2 infection. Antigen detection (AD) tests are more rapid, less laborious, and less expensive alternatives but still require clinical validation. (2) Methods: This study compared the clinical performance of five AD tests, including four rapid AD (RAD) tests (biotical, Panbio, Healgen, and Roche) and one automated AD test (VITROS). For that purpose, 118 (62.8%) symptomatic patients and 70 (37.2%) asymptomatic subjects were tested, and results were compared to RT-PCR. (3) Results: The performance of the RAD tests was modest and allowed us to identify RT-PCR positive patients with higher viral loads. For Ct values =25, the sensitivity ranged from 93.1% (95% CI: 83.3-98.1%) to 96.6% (95% CI: 88.1-99.6%), meaning that some samples with high viral loads were missed. Considering the Ct value proposed by the CDC for contagiousness (i.e., Ct values =33) sensitivities ranged from 76.2% (95% CI: 65.4-85.1%) to 88.8% (95% CI: 79.7-94.7%) while the specificity ranged from 96.3% (95% CI: 90.8-99.0%) to 99.1% (95% CI: 95.0-100%). The VITROS automated assay showed a 100% (95% CI: 95.5-100%) sensitivity for Ct values =33, and had a specificity of 100% (95% CI: 96.6-100%); (4) Conclusions: Compared to RAD tests, the VITROS assay fully aligned with RT-PCR for Ct values up to 33, which might allow a faster, easier and cheaper identification of SARS-CoV-2 contagious patients.
| Discipline / Specialty Area | Score |
|---|---|
| Family Medicine (FM)/General Practice (GP) | |
| General Internal Medicine-Primary Care(US) | |
| Infectious Disease | |
| Respirology/Pulmonology | |
| Public Health | |
| Pediatric Emergency Medicine | |
| Hospital Doctor/Hospitalists | |
| Internal Medicine | |
| Pediatrics (General) | |
| Emergency Medicine | |
| Pediatric Hospital Medicine | |
The sample size is relatively small and the reference standard used here (PCR) is not an accurate test. So, I am not sure whether the findings are valid.
Rapid diagnostic tests are urgently needed in the emergency department context to facilitate bed assignments and for discharge plans for possible and likely COVID patients. They are coming but in a highly variable way. This study helps orient current and future users about their accuracy and utility.
Good information at this point in time, but the field is rapidly evolving and this information may not stay relevant.
The determination of the most accurate and rapid detection for SARS-CoV-2 is of utmost importance to stop the spread of the pandemic. This study evaluated 5 types of rapid tests compared with PCR as the gold standard. They all scored well, but the automated VITROS test was 100% sensitive and 100% specific at even low viral loads. The authors report a conflict of interest with the company. Hopefully, others will replicate the methods.
We need a test that is highly sensitive and specific. Few rapid tests have been able to do the job.
With the exception of the information on the VITROS test, I think the primary care physicians in my institution already know the general conclusions of this study: namely, the issues with sensitivity in patients with low viral load.
Emergency physicians commonly evaluate patients with COVID-19 infection and exposure. Timely diagnosis of COVID-19 is important to provide appropriate treatment and judicious laboratory evaluation. Since this infection is potentially contagious, it will allow for timely isolation to prevent the spread. This study provided a comparison of the clinical performance of several RAD tests. The implementation of RAD tests in mass screening programs may help to decrease the burden on laboratories. However, RAD tests mostly identified patients when there was a high viral load.
As a pediatrician, the validation of antigen tests in adults provides a likely range for sensitivity and specificity. The tests in my pediatric population need to be validated to confirm. Given the cost and accuracy of the tests, masking and testing may help us transition out of this pandemic.
Good comparison of PCR with direct antigen test (both worked).
With the plethora of COVID tests available it is hard to decide which test to invest in/use. This study by comparing different RAD tests with RT-PCR testing offers some guidance and sheds light on a different technology - chemiluminescence, that may be more useful than the conventional immunochromatography.
The 3 RAD tests showed an acceptable sensitivity only for samples corresponding with higher viral loads. Even so, some samples were miscategorized from both symptomatic and asymptomatic patients. The AD assay performed the best (100% sensitivity) and RAD tests reported insufficient sensitivity. The automated assay could be proposed as a first-line testing method for the detection of potential contagious cases.
This study compared several rapid antigen detection assays and found less deficiency in disease detection in patients with lower viral loads. The Automated detection assay was significantly more effective. This kind of information is most important for persons developing mass screening programs.