Here's the thing, letting young people get back to work won't save the economy or even boost it in any meaningful way. A huge portion of the workforce is over 40, and people over 40 in the US aren't in the best of shape. So I'm unsure of what "letting the young and healthy" getting back to work is supposed to achieve? Most of them are probably already working, either in essential grocery, fast food, healthcare jobs, or can work from home, since younger people tend to have jobs in tech. Young people also feature heavily in food service jobs, but even if "we opened up," that sector isn't going to do anywhere near pre-Covid business since no one will be comfortable crowding restaurants, bars and cafes for awhile.
The path to a wholesale getting back to work is test, test, test and knowing the particulars of this virus down to its last atom. If we find out it has a mortality and hospitalization rate around flu levels and if it's confirmed immunity is guaranteed after getting it, then we can confidently apply a set of strategies to reopen commerce. People with immunity can get back to work and the typical consumer activity of shopping, eating at restaurants, going to bars, theaters, etc. If we find out the virus is no more dangerous than the flu, then people will be comfortable in those crowded social settings. But we don't know much right now.