保证
已经证实无症状带毒的可能性
即，自身无症状，抵抗力强，不发病，但可传播
这个太可怕，都是命

https://www.heraldnet.com/news/new-virus-from-china-reaches-us-and-snohomish-county/
重点
At that time he showed no symptoms, health officials said.
“In this case, we don’t believe even if we had active screening at the airport that this patient would have been picked up, because at the time we don’t believe the patient had any symptoms of the fever,” said John Weissman, the Washington state secretary of health.