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Clinical characteristics, treatments and outcomes of hospitalised COVID-19 patients across pandemic waves at a tertiary acute care hospital in Narita, Japan: a single-centre retrospective observational study

Year: 2026

Type: article

Abstract: OBJECTIVE: This study aims to describe the characteristics of hospitalised COVID-19 patients in a tertiary care hospital close to an international airport in Japan and to compare these characteristics among different waves during the pandemic. DESIGN: Retrospective observational study. SETTING: Tertiary care centre in Japan. PARTICIPANTS: All patients diagnosed with COVID-19 who were hospitalised between January 2020 and April 2022 were included. MEASUREMENTS: Clinical characteristics, characteristics of admission, treatments and outcomes were investigated and compared among six pandemic waves. RESULTS: A total of 827 patients were included. The median age was 58.0 years. More than half of the patients (58.3%) had at least one comorbidity. The majority of patients (89.0%) were domestically infected patients admitted under the Infectious Diseases Law, while the remaining patients (11.0%) were those diagnosed during airport quarantine and admitted under the Quarantine Act. Hospital-acquired COVID-19 infection occurred in 7.0% of cases, and mainly during the sixth wave. Overall, some form of oxygen therapy, high-flow oxygen devices, invasive mechanical ventilation (IMV) and extracorporeal membrane oxygenation was provided in 46.3%, 10.4%, 4.5% and 1.5% of cases, respectively. Only 1.8% of patients were treated in the intensive care unit (ICU), and 59.5% of patients on IMV were managed in the non-ICU ward. The in-hospital mortality rate was 5.8%. Median age, percentages of some comorbidities, vaccination coverage, medications for COVID-19, types of supportive care and ICU admissions differed significantly among waves. CONCLUSIONS: This study suggests that patient characteristics, vaccination coverage, standard of treatment and severity of illness changed across waves during the COVID-19 pandemic. Intensive care delivery in non-ICU wards was unavoidable due to limited ICU capacity, which may be a key consideration when preparing for future pandemics.

Source: BMJ Open

DOI: 10.1136/bmjopen-2025-109380