Real-World Treatment Outcomes in the First and Subsequent Coronavirus Disease 2019 (COVID-19) Hospital Clusters

We experienced 10 coronavirus disease 2019 (COVID-19) hospital clusters between November 2020 and September 2023 and retrospectively examined whether the introduction of hospital cluster countermeasures improved patient prognosis.

We compared the first hospital cluster, in which infection prevention measures were insufficient, vaccines were not introduced, and antiviral drugs were not available (Phase 1), and the second or subsequent hospital clusters, when the abovementioned measures were improved (Phase 2).

In Phase 2, the number of COVID-19 patient deaths within 30 days, infection rate in patients who shared a room with an infected patient, and infection rate among medical workers were reduced. Survival rates within 30 days did not differ significantly between Phases 1 and 2. In Phase 2, the survival rate was higher in females than in males and in groups treated with ensitrelvir and molnupiravir than in those treated with remdesivir.

Countermeasures against hospital clusters require comprehensive measures, such as infection prevention, vaccination, rapid diagnosis, and antiviral drug administration. Antiviral drugs may shorten hospital clusters by rapidly suppressing severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in patients.