The SARS coronavirus of 2003, which was more severe and deadly, had a considerably longer duration of immunity.

2003 年的 SARS 冠状病毒更为严重和致命，其免疫力持续时间要长得多。

COVID-19 is caused by a virus called SARS-CoV-2, or severe acute respiratory symdrome coronavirus 2, because it's genetically similar to the SARS coronavirus, which was responsible for the SARS outbreak in 2002.

COVID-19由SARS-CoV-2病毒（2型严重呼吸综合征冠状病毒）引起；它的基因序列与SARS冠状病毒相似；SARS病毒是于02年底出现、03年蔓延，引起严重急性呼吸综合征（SARS）的元凶。