Treatment with ensitrelvir for COVID-19 in hospitalized patients of very advanced age: Case series

Ensitrelvir fumaric acid (ensitrelvir) is an orally active 3C-like protease inhibitor used to treat severe acute respiratory syndrome coronavirus 2 infection. Ensitrelvir was granted an emergency use authorization in Japan in 2022, but reports on the effectiveness and safety of ensitrelvir in actual clinical settings are limited.

Here, we report a case series of 9 patients with laboratory-confirmed symptomatic coronavirus disease of 2019 (COVID-19) who completed a 5-day course of ensitrelvir at Tomita Hospital from November 2022 to April 2023. Data on clinical symptoms, oxygen saturation, and food intake were collected for 14 days, beginning on the first day of ensitrelvir administration. The outcome of COVID-19 in each patient was also evaluated during this period.

All patients were female, 80 years old or older, and the mean age was 90.2 ± 5.5 years. All patients received ensitrelvir within 2 days after the onset of COVID-19. At baseline, 7 among the 9 patients had their body temperature above 37.5 °C and all of them had oxygen saturation levels of 94% or higher. All patients recovered without worsening of COVID-19, and none received oxygen or additional antiviral drugs during the observation period; no deaths were reported within 14 days. After receiving ensitrelvir for 5 days, all patients had resolution of fever (<37 °C). There was no significant decrease in food intake of patients due to COVID-19. All patients maintained oxygen saturation above 93%.

Our results provide information on the real-world usage of ensitrelvir in elderly, hospitalized patients with COVID-19, and suggests that ensitrelvir is an option for treatment of COVID-19 in these population.