三級病原定義為空氣傳播的致病生物，四級是空氣傳播的致命生物，新冠似乎更符合四級的定義

來源: 朱頭山於 2021-01-28 10:48:50 [博客] [舊帖] [給我悄悄話] 本文已被閱讀：次

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