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COVID-19 PCR test performance on samples stored at ambient temperature
Nihat Bugra Agaoglu1, Jale Yildiz2, Ozlem Akgun Dogan3
1Genomic Laboratory (GLAB), Umraniye Teaching and Research Hospital, University of Health Sciences, Istanbul, Turkey; Department of Medical Genetics, Umraniye Teaching and Research Hospital, University of Health Sciences, Istanbul, Turkey.
Insights
Storing COVID-19 swab samples at room temperature for up to six days is viable. This finding supports accessible diagnostic testing during the pandemic, especially in resource-limited settings.
Area of Science:
- Virology
- Molecular Diagnostics
- Public Health
Background:
- The COVID-19 pandemic necessitated large-scale diagnostic testing, overwhelming global laboratory capacity.
- Standard protocols required cold chain compliance for swab sample transport and storage, posing logistical challenges.
- Alternative storage methods were needed to maintain sample integrity under resource-limited conditions.
Purpose of the Study:
- To evaluate the impact of ambient temperature versus refrigerated storage on COVID-19 real-time PCR assay results.
- To determine the stability of viral RNA in nasopharyngeal and oropharyngeal swab samples under different storage conditions.
Main Methods:
- Collected 30 positive COVID-19 nasopharyngeal/oropharyngeal swab samples.
- Stored samples at ambient temperature (22 ± 2 °C) and +4 °C.
- Performed real-time PCR assays to assess viral RNA stability.
Main Results:
- All samples stored at ambient temperature remained PCR positive for at least six days.
- No false-negative results were observed in samples stored at ambient temperature.
- Refrigerated samples also maintained PCR positivity, but ambient storage proved effective.
Conclusions:
- Transporting and storing COVID-19 swab samples at ambient temperature for up to six days is acceptable.
- This method offers a viable alternative for resource-limited settings during the pandemic.
- Relaxing cold chain requirements can improve diagnostic accessibility and laboratory workflow.
Abstract:
The WHO-named Coronavirus Disease 2019 (COVID-19) infection had become a pandemic within a short time period since it was detected in Wuhan. The outbreak required the screening of millions of samples daily and overwhelmed diagnostic laboratories worldwide. During this pandemic, the handling of patient specimens according to the universal guidelines was extremely difficult as the WHO, CDC and ECDC required cold chain compliance during transport and storage of the swab samples. The aim of this study was to compare the effects of two different storage conditions on the COVID-19 real-time PCR assay on 30 positive nasopharyngeal and/or oropharyngeal samples stored at both ambient temperature (22 ± 2 °C) and +4 °C. The results revealed that all the samples stored at ambient temperature remain PCR positive for at least six days without any false-negative result. In conclusion, transporting and storing these types of swab samples at ambient temperature for six days under resource-limited conditions during the COVID-19 pandemics are acceptable.
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