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-1 9 (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.& COPY; 2022 The Author(s). Published by Elsevier Inc. on behalf of Association for Professionals in Infection Control and Epidemiology, Inc. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/)