Unclear. Can't find a link, but I recall reading that if you were within 50m (?) of a norovirus patient when they vomited, you had a noticeable chance of catching the bug yourself.
social distancing is the cancelation of conferences (google canceled theirs), not having sporting events (italy), not sending kids to school, etc, etc.
I see this phrase used to describe maintaining a larger personal space, like one or two meters, which is what I had in mind.
Check out the economist cover article for this week. Goes over it in detail.