Letter to the Editor: Case of the Index Patient Who Caused Tertiary Transmission of Coronavirus Disease 2019 in Korea: the Application of Lopinavir/Ritonavir for the Treatment of COVID-19 Pneumonia Monitored by Quantitative RT-PCR

Abstract

I am grateful that Dr. Lim and his colleagues reported a case of COVID-19 that caused tertiary transmission in Korea and added information about the novel infectious disease. 1 In this report, the authors emphasized the decrease in viral titer due to the effects of antiviral administration. However, I would like to discuss what to look out for when interpreting the causal relationship between laboratory results and therapeutic effects.Lopinavir and ritonavir (LPV/r) is considered a promising treatment option for COVID-19 based on the 2003 SARS treatment experience. 2,3 However, care should be taken when administering because there are no or little clinical evidence for the new virus, SARS-CoV-2. I have treated with LPV/r as an antiviral agent in patients with pneumonia caused by COVID-19, but the disease course has not improved dramatically. 4 Fortunately, the patient did not develop acute respiratory failure, but it was not clear whether it was an effect of antiviral drug.According to the Center for Laboratory Control of Infectious Diseases in KCDC, the upper limit of Ct value for positive RT-PCR of SARS-CoV-2 is 35, and the negative criterion is Ct value 37 or higher. In this case report, it is difficult to determine that the test result is positive because the Ct value is 35.66 on day 10, the day of the antiviral treatment. If there was a virus, it would have remained a very low titer. Since LPV/r was administered during the virus titer reduction from 30.71 (day 9) to 35.66 (day 10), I think two consecutive negative results are more likely to be due to the natural history of the disease than to antiviral agents. Furthermore, the authors did not explain why Ct values are consistently detected near positive criteria from day 4 of treatment despite the continued use of antiviral agents.

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Repurposing Antiviral Protease Inhibitors Using Extracellular Vesicles for Potential Therapy of COVID-19

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