As no specific therapeutic agents have been established yet for coronavirus disease 2019 (COVID-19),the illness caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), symptomatic therapy is the mainstay of treatment. Although the “Concept of antiviral treatment for COVID-19, First edition” published by the Japanese Association for Infectious Diseases recommends the use of antiviral medication for infected individuals over the age of 50 years, we have documented the case of a 73-year-old woman with COVID-19 pneumonia who improved without antiviral medication. The patient became infected with SARS-CoV-2 on the cruise ship, Diamond Princess, and first tested positive for SARS-CoV-2, by the RT-PCR test, on February 15, 2020. She was admitted to another hospital with fever and pneumonia on February 16, and on February, the pneumonia worsened in severity, she was transferred to our hospital. However, her condition improved spontaneously within a few days, without any antiviral medication. This report is very valuable for documenting the natural history of COVID-19 pneumonia and can be considered as a reference case for formulating strategies for antiviral drug administration for COVID-19 patients in the future.
