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Efficient SARS-CoV-2 Quantitative Reverse Transcriptase PCR Saliva Diagnostic Strategy utilizing Open-Source Pipetting Robots
Published on: February 11, 2022
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A simple algorithm based on initial Ct values predicts the duration to SARS-CoV-2 negativity and allows more
Olympia E Anastasiou1, Vu Thuy Khanh Le-Trilling1, Mirko Trilling1
1Institute for Virology, University Hospital Essen, University of Duisburg-Essen, Duisburg-Essen, NRW, Germany.
Diagnostic Microbiology and Infectious Disease
|April 23, 2023
Summary
Lower initial Ct values in SARS-CoV-2 testing indicate longer periods of infectivity. This study suggests optimizing diagnostic PCR resources by adjusting retesting strategies based on initial viral load, crucial for pandemic management.
Area of Science:
- Virology
- Epidemiology
- Molecular Diagnostics
Background:
- Diagnostic capacity for quantitative reverse transcription-polymerase chain reactions (qRT-PCRs) is a critical bottleneck during pandemics and epidemic waves.
- Effective retesting strategies are needed for test-to-release from isolation and return-to-work protocols.
Purpose of the Study:
- To optimize retesting regimens for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) by investigating the association between initial Ct values and time to test negativity.
- To determine the correlation between initial Ct values and the duration until SARS-CoV-2 RNA becomes undetectable or Ct exceeds 30.
Main Methods:
- Retrospective analysis of respiratory sample testing data for SARS-CoV-2 RNA from March 2020 to January 2022.
- Investigated the relationship between initial cycle threshold (Ct) values and the time required to reach test negativity or a Ct value >30.
Main Results:
- Lower initial Ct values (indicating higher viral load) were significantly associated with longer periods of SARS-CoV-2 RNA positivity.
- Median time to negativity ranged from 5 days (Ct ≥35) to 20 days (Ct <20).
- Time to negativity was longer in adults vs. children, for wild-type SARS-CoV-2 vs. other variants, and in ICU patients.
Conclusions:
- Initial Ct values are a strong predictor of the duration of SARS-CoV-2 RNA positivity.
- An adjusted retesting strategy based on initial Ct values can optimize PCR resource allocation.
- This approach supports efficient management of isolation and return-to-work decisions during public health crises.
