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Clin Chem. Potential false-negative nucleic acid testing results for Severe Acute Respiratory Syndrome Coronavirus 2 from thermal inactivation of samples with low viral loads

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  • Clin Chem. Potential false-negative nucleic acid testing results for Severe Acute Respiratory Syndrome Coronavirus 2 from thermal inactivation of samples with low viral loads


    Clin Chem. 2020 Apr 4. pii: hvaa091. doi: 10.1093/clinchem/hvaa091. [Epub ahead of print]
    Potential false-negative nucleic acid testing results for Severe Acute Respiratory Syndrome Coronavirus 2 from thermal inactivation of samples with low viral loads.


    Pan Y1,2,3, Long L4,5,6, Zhang D1,2,3, Yan T7, Cui S1,2,3, Yang P1,2,3, Wang Q1,2,3, Ren S4,5,6.

    Author information




    Abstract

    BACKGROUND:

    Corona Virus Disease-2019 (COVID-19) has spread widely throughout the world since the end of 2019. Nucleic acid testing (NAT) has played an important role in patient diagnosis and management of COVID-19. In some circumstances, thermal inactivation at 56 ?C has been recommended to inactivate Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) before NAT. However, this procedure could theoretically disrupt nucleic acid integrity of this single-stranded RNA virus and cause false negatives in real-time polymerase chain reaction (RT-PCR) tests.
    METHODS:

    We investigated whether thermal inactivation could affect the results of viral NAT. We examined the effects of thermal inactivation on the quantitative RT-PCR results of SARS-CoV-2 particularly with regard to the rates of false-negative results for specimens carrying low viral loads. We additionally investigated the effects of different specimen types, sample preservation times and a chemical inactivation approach on NAT.
    RESULTS:

    Our work showed increased Ct values in specimens from diagnosed COVID-19 patients in RT-PCR tests after thermal incubation. Moreover, about half of the weak-positive samples (7 of 15 samples, 46.7%) were RT-PCR negative after heat inactivation in at least one parallel testing. The use of guanidinium-based lysis for preservation of these specimens had a smaller impact on RT-PCR results with fewer false negatives (2 of 15 samples, 13.3%) and significantly less increase in Ct values than heat inactivation.
    CONCLUSION:

    Thermal inactivation adversely affected the efficiency of RT-PCR for SARS-CoV-2 detection. Given the limited applicability associated with chemical inactivators, other approaches to ensure the overall protection of laboratory personnel need consideration.
    ? 2020 American Association for Clinical Chemistry.



    KEYWORDS:

    COVID-19; False negative; Nucleic Acid Test; RT-PCR; SARS-CoV-2; Thermal Inactivation


    PMID:32246822DOI:10.1093/clinchem/hvaa091

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