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Longitudinal SARS-CoV-2 Testing among the Unvaccinated Is Punctuated by Intermittent Positivity and Variable Rates of
Shawn E Hawken1, Subhashini A Sellers2, Jason R Smedberg1
1Clinical Microbiology Laboratory, McLendon Clinical Laboratories, UNC Medical Center, Chapel Hill, North Carolina, USA.
Microbiology Spectrum
|March 22, 2022
Summary
Interpreting severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) test C-values requires caution, especially in unvaccinated individuals. Prolonged positivity and oscillating results complicate clinical decisions regarding infection control and treatment.
Area of Science:
- Virology
- Infectious Diseases
- Clinical Diagnostics
Background:
- The COVID-19 pandemic presents challenges with vaccine breakthroughs, reinfections, and the spread of variants of concern (VOCs).
- Accurate interpretation of longitudinal severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) test results is vital for managing infection control and treatment decisions.
- Real-time reverse transcription (RT)-PCR tests provide C-values inversely correlated with RNA quantity but are approved only for qualitative interpretation.
Purpose of the Study:
- To analyze the duration of SARS-CoV-2 positivity and clinical outcomes in an unvaccinated patient cohort.
- To investigate the characteristics of patients with prolonged SARS-CoV-2 positivity.
- To highlight challenges in using C-values for clinical decision-making in unvaccinated individuals.
Main Methods:
- Retrospective review of 72,217 SARS-CoV-2 positive tests.
- Identification of 264 patients with longitudinal positivity before vaccination and VOC circulation.
- Categorization of patients into short-term (≤28 days) and prolonged (>28 days) positivity groups.
Main Results:
- Longitudinal positivity was categorized as short-term (78%) or prolonged (22%).
- While C-values generally increased over time, some patients showed increased RNA or prolonged detection.
- Oscillating positive/negative results were more frequent in the prolonged positivity group, with 22% of these patients critically ill or deceased.
Conclusions:
- Caution is essential when interpreting SARS-CoV-2 C-values as a proxy for infectivity or severity in unvaccinated individuals.
- Clinical context is crucial for guiding patient care decisions, as C-values alone can be misleading.
- Prolonged SARS-CoV-2 positivity presents unique challenges for managing unvaccinated patients.
