A Study on Requirement of Cold Chain Maintenance for Reliable Testing of SARS-CoV-2 Sample

摘要

Coronavirus Disease 2019 (COVID-19) has been haunting the world since December 2019 and has grown to pandemic proportions from March 2020. Even after a full year of research and study, the most effective way to control the spread of this infection is early diagnosis and isolation of the cases. Real-time Reverse Transcription Polymerase Chain Reaction (RT-PCR) is considered the standard test all over the world for the diagnosis of Severe Acute Respiratory Syndrome Corona Virus 2 (SARS-CoV-2) infection. All the sample collection guidelines have recommended stringent maintenance of the cold chain for the sample transport. However, it is not possible for the resource constrained developing countries with inadequate infrastructure to comply with these guidelines all the time.Aim: To determine necessity of stringent transport criteria and the effect of temperature on the clinical sensitivity of a RT-PCR assay for diagnosis of SARS-CoV-2 infection.Materials and Methods: In this prospective experimental study conducted in November 2020, 49 positive samples were kept at ambient room temperature and were tested everyday with RTPCR for the detection of SARS-CoV-2 Ribonucleic Acid (RNA). The samples were also kept under refrigeration at 4?°C and were also tested by RT-PCR and the results were compared with their respective counterparts kept at room temperature till nine days. Python Jupiter notebook SciPy and Anaconda software was used for statistical analysis.Results: It was observed that the positivity of the RT-PCR results were not deteriorated till five days and there was no significant deterioration even after nine days of samples being stored at room temperature suggesting that even if the viral RNA itself is not stable outside strict temperature control but small fragment or target genetic sequences are enough for detection of virus by RT-PCR.Conclusion: It is possible to keep samples at this ambient temperature for five days without any loss of positivity in RT-PCR.