Before this outbreak, six coronaviruses had been identified in humans. Four caused relatively mild cold-like symptoms while the other two, Sars and Middle East respiratory syndrome (Mers), can be fatal.

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此次疫情爆发之前，已知的人类冠状病毒有6种。四种引起相对轻度的类似感冒症状，而另外两种——非典和中东呼吸综合征(MERS)——可能致命。