by Tawny Hammett, M.S. JHU Alumna
The COVID-19 pandemic has transcended a mere influenza-like disease, showcasing a range of severity from mild cold symptoms to multi-organ failure and death1. Given the spectrum of COVID-19’s virulence, testing is a crucial epidemic surveillance strategy to detect, contain, and mitigate viral spread throughout the population. In April 2020, the FDA granted Emergency Use Authorization (EUA) for the first at-home collection in vitro diagnostic device for COVID-19, a molecular test using RT-PCR conducted in CLIA certified labs2. Since then, direct-to-consumer (DTC) testing has proliferated, with multiple companies providing COVID-19 tests supplemented with telemedicine and result dashboards.
These kits detect active infection from nasal swabs or saliva samples. At home, self-administered antibody tests used to determine past exposure to the virus are currently considered, such as REACT (real-time assessment of community transmission) conducted by the Imperial College London in the UK3. More excellent safety for patients and healthcare workers who may have otherwise been exposed during on-site clinical sampling and convenience are some of the advantages DTC COVID-19 RT-PCR kits offer. While quantitative RT-PCR is considered the gold standard for detecting COVID-19 due to its sensitivity and specificity rates, DTC tests using the CLIA lab conducted RT-PCR method pose challenges in the prolonged sample to answer time and testing outside of the diagnostic window, which can lead to false negatives4.
These testing error deficiencies could be ameliorated by more frequent testing, even if using less sensitive tests because viral kinetics constitute a significant factor in accurate viral detection. COVID-19’s viral kinetics can be characterized by latency, growth, peak, and decline phases, where an infected individual experiences a low viral load during incubation, followed by exponential viral growth, peak viral load, and then eventual decline5. Given the varying stages, even highly sensitive tests may inaccurately report infection if administered at an individual’s illness phase, where viral replication would have been still relatively low4. The diagnostic window issue is not exclusive to DTC tests, but rather, DTC may confer a more significant benefit in providing tests more frequently if self-administered antigen tests for active infection are FDA approved.
An antigen test detects nucleocapsid protein from SARS-CoV-2 and can be administered at point-of-contact using from nasal and nasopharyngeal swabs. There are two tests currently FDA approved at this time, but they are only allowed in inpatient care settings operating under a CLIA Certificate Waiver, Compliance, or Accreditation6. Antigen tests have about an 80% sensitivity rate compared to RT-PCR, but the greater testing frequency may offset the gap. Additionally, antigen tests are more rapid (< 30 minutes) and less expensive4.
In the pandemic’s current state, a robust epidemic surveillance system could enhance its strategy to include more frequent testing that may have lower sensitivity rather than solely depending on single tests with higher sensitivity. Furthermore, at home, a self-administered examination could influence sweeping changes in health behavior. Patients may become more accustomed to the convenience and ease of using at-home testing, adopting these practices for long term use in a range of other laboratory tests. Changes in perceived societal and economic obligations to public health may also shift.
People may feel a greater need to stay at home if they are sick to protect those around them, and employers opt to send employees at-home kits for rapid testing if they’re feeling ill. Though the pandemic battle still wages on, we can find small reprieve, knowing we’re transforming the future of consumer-driven healthcare.
1.) Gao Y, Li T, Han M, et al. Diagnostic utility of clinical laboratory data determinations for patients with the severe COVID-19. J Med Virol. 2020;92(7):791-796. doi:10.1002/jmv.25770
3.) We test a home antibody kit for tracking Covid-19. Video. https://www.nature.com/articles/d41586-020-01677-y
4.) Shyu D, Dorroh J, Holtmeyer C, et al. Laboratory Tests for COVID-19: A Review of Peer-Reviewed Publications and Implications for Clinical UIse. Mo Med. 2020;117(3):184-195.
5.) Daniel B Larremore, D., et al. Test sensitivity is secondary to frequency and turnaround time for COVID-19 surveillance. medRxiv 2020.06.22.20136309; doi: https://doi.org/10.1101/2020.06.22.20136309
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