High mortality and morbidity among vaccinated residents infected with the SARS-CoV-2 Omicron variant during an outbreak in a nursing home in Kyoto City, Japan

BACKGROUND: Outbreaks of coronavirus disease 2019 (COVID-19) in long-term care facilities are associated with mortality, although vaccination have contributed to improvements. This study reports clinical impacts of a COVID-19 outbreak in a nursing home for elderly individuals in Kyoto City, Japan. METHODS: We performed epidemiologic and molecular investigations of the outbreak and characterized outcomes of the nursing home residents. RESULTS: During the outbreak period, a total of 31 residents (39.2%) and 26 staff members (49.1%) were infected with COVID-19. All residents and staff received two doses of a vaccine approximately 7 months prior. Ten residents with severe hypoxemia could not be transferred to a hospital due to a shortage of beds for COVID-19 patients. Within 90 days of the onset of the outbreak, 8 residents with COVID-19 (25.8%) died. A total of 48.4% of residents with COVID-19 developed 1 or more comorbidities. Viral genome analysis showed that the outbreak was caused by the Omicron BA.1.1.2 variant. CONCLUSIONS: Despite vaccination, high mortality and morbidity were observed in the COVID-19 outbreak due to the Omicron variant. Limiting medical care for residents with COVID-19 in facilities that experience ongoing outbreaks may be needed to reduce the risk of mortality among nursing home residents.