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Practical strategies for SARS-CoV-2 RT-PCR testing in resource-constrained settings.
Meredith S Muller1, Srijana B Chhetri1, Christopher Basham1
1Institute of Global Health and Infectious Diseases, University of North Carolina School of Medicine, Chapel Hill, NC, USA.
Diagnostic Microbiology and Infectious Disease
|July 19, 2021
Summary
Self-administered nasal swabs offer a viable alternative to nasopharyngeal sampling for detecting SARS-CoV-2. Polyester flocked and 3D-printed swabs show promising sensitivity, especially when preserved for transport, aiding in widespread COVID-19 testing capacity.
Area of Science:
- Virology
- Public Health
- Medical Diagnostics
Background:
- Nasopharyngeal sampling presents limitations for scaling SARS-CoV-2 testing capacity.
- Development of alternative, user-friendly sample collection methods is crucial for pandemic response.
- Self-testing options can significantly increase accessibility and throughput for infectious disease diagnostics.
Purpose of the Study:
- To evaluate the efficacy of self-administered nasal mid-turbinate swabs as an alternative to nasopharyngeal sampling for SARS-CoV-2 detection.
- To compare the performance of polyester flocked swabs and 3D-printed swabs in detecting SARS-CoV-2.
- To assess the impact of different transport media and storage conditions on viral RNA stability in nasal samples.
Main Methods:
- Piloted collection of nasal mid-turbinate swabs (polyester flocked and 3D-printed) from 275 participants.
- Samples were placed in viral transport media or RNA stabilization agents.
- Evaluated SARS-CoV-2 detection sensitivity via PCR compared to nasopharyngeal swabs and assessed viral RNA stability under various conditions, including room temperature storage for up to 7 days. Pooling strategies (at collection vs. in-lab) were also examined.
Main Results:
- Polyester flocked nasal swabs demonstrated 87% sensitivity (95% CI 79-92%) for detecting SARS-CoV-2 compared to nasopharyngeal sampling, missing samples with low viral loads (<10^6 copies/mL).
- 3D-printed nasal swabs exhibited comparable sensitivity to flocked swabs.
- Using RNA preservative reduced the log decrease in viral copies, maintaining sample integrity for up to 7 days at room temperature. Both pooling methods successfully detected samples with >10^5 viral copies/mL.
Conclusions:
- Self-administered nasal mid-turbinate swabs, particularly polyester flocked types, are a promising alternative for SARS-CoV-2 testing, offering improved ease of use and potentially increased testing capacity.
- RNA stabilization agents enhance viral RNA stability in nasal swabs, allowing for flexible transport and storage.
- Pooling strategies can be effectively implemented at the point of collection or in the lab to maximize testing efficiency for SARS-CoV-2.
