Two cases of novel coronavirus infection (COVID-19) with transient viral elevation using semi-quantitative real-time reverse transcription PCR and symptom relapse after completion of 10 days of favipiravir treatment

The coronavirus disease of 2019 (COVID-19), which began in Wuhan, China, at the end of 2019, is spreading around the world and causing many deaths, mainly from pneumonia. Currently, there are no specific drugs to treat COVID-19, and existing antiviral drugs are being used as an alternative. One of these is favipiravir, a new type of influenza drug. However, its efficacy, dosage, and duration of administration are still under study. In this case study, we administered favipiravir to patients with COVID-19 and determined the viral load of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the COVID-19 pathogen, using semi-quantitative real-time reverse transcription PCR in sputum samples. We report on two patients in whom the viral load increased again after completion of 10 days of favipiravir treatment and a transient relapse of symptoms was observed.