Three coronavirus disease 2019 cases with acute progression of respiratory failure were improved after methylprednisolone therapy

Ririko Fujiyoshi, Masaki Okamoto, Yoji Nagasaki, Yoshihisa Tokunaga, Kiyomi Furuya, Masatoshi Shimo, Sayoko Ishihara, Hiroaki Takeoka, Yoshiko Naitou-Nishida, Takashi Nouno, Satoshi Sakamoto, Hiroyoshi Yamada, Ryo Yano, Hiromi Iwasaki, Tomoaki Hoshino, Shigeki Morita