The scientists said we cannot know exactly how to respond. Every day was a potential new battle plan. History is dictating our moves because it is the only thing we have with factual evidence, versus anecdotal. There is no way to know how effective our measures are, because this is a biological threat to which there are no emergency response manuals.
The reason behind the social distancing efforts and mandatory closures is too alleviate the burden to our health care system and responders, because we can quickly be overrun with sick Americans that will be turned away from medical care due to a lack thereof.