Impact of prefecture-level intensive care unit congestion on mortality in severe COVID-19 patients: a retrospective observational study in Japan. - Iwasaki, Yudai; Ogura, Takayuki; Ohbe, Hiroyuki; Hashimoto, Satoru; Kushimoto, Shigeki; Ohshimo, Shinichiro; Shime, Nobuaki; Takeda, Shinhiro (BMC Infectious Diseases, 2025)