Heat inactivation decreases the qualitative real-time RT-PCR detection rates of clinical samples with high cycle threshold values in COVID-19

SARS-CoV-2 has caused COVID-19 pandemic globally in the beginning of 2020, and qualitative real-time RT-PCR has become the gold standard in diagnosis. As SARSCoV-2 with strong transmissibility and pathogenicity, it has become a professional consensus that clinical samples from suspected patients should be heat inactivated at 56°C for 30 min before further processing. However, previous studies on the effect of inactivation on qualitative real-time RT-PCR were conducted with diluted samples rather than clinical samples. The aim of this study was to investigate whether heat inactivation on clinical samples before detection will affect the accuracy of qualitative real-time RT-PCR detection. All 46 throat swab samples from 46 confirmed inpatients were detected by qualitative real-time RT-PCR directly, as well as after heat inactivation. Heat-Inactivation has significantly influenced the qualitative detection results on clinical samples, especially weakly positive samples. The results indicate the urgency to establish a more suitable protocol for COVID-19 clinical sample's inactivation.