Very little was known about it ( though droplet transmission was identified as a possible source of infection ) ; and （乙）对疾病所知不多（尽管飞?传染被认为是可能的传播途径） ；及
2.
It is spread through droplet transmission when an infected person coughs or sneezes . this has a range of about 1 - m 它是通过被感染者咳嗽或打喷嚏时所产生的分泌物来传播的。传播范围大约是1公尺。
