https://www.who.int/emergencies/ ... nd-how-to-use-masks
If you are healthy, you only need to wear a mask if you are taking care of a person with suspected 2019-nCoV infection.
Wear a mask if you are coughing or sneezing.
Masks are effective only when used in combination with frequent hand-cleaning with alcohol-based hand rub or soap and water.
If you wear a mask, then you must know how to use it and dispose of it properly.
Maintain social distancing
Maintain at least 1 metre (3 feet) distance between yourself and anyone who is coughing or sneezing.
你怎么知道谁会咳嗽打喷嚏?根本无法防止。
这病说话都还会传染, 这个警告根本无用。
大量检测作用是很有限的, 你今天没有, 明天就没有吗?你能天天检查吗?无非是跟着中共调调抹黑。