After initial assertions that the wearing of face masks was an unnecessary public health tool in the prevention of the spread of Covid-19, the advice coming out of the Centers for Disease Control (CDC) suddenly changed. In early April, the CDC issued new guidelines advising people to wear face coverings in public settings where social distancing is difficult.

中文翻译：

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暴露的行为

在最初断言戴口罩是预防 Covid-19 传播的不必要的公共卫生工具之后，疾病控制中心 (CDC) 的建议突然改变了。4 月初，CDC 发布了新指南，建议人们在难以保持社交距离的公共场所戴口罩。