If I was running economic recovery* for this thing, here's what I'd be thinking about:

*I was ec recovery manager for an NGO after the Japan tsunami. different, but not totally unqualified

UBI, obviously, but I'll come back to the complexities of that. Meantime, I'd be jumping up and down for an immunity test and preparing a mechanism to get those workers back into the economy in a flexible way once it's rolled out.

Maybe it would be a gov't-run pool of immune people to do delivery for any business that needs them, or to do customer interaction. Or maybe a giant temp service. Obviously this would be voluntary; the point is not to pull people away from their previous job or family needs.

I'd also be providing support to small business trying to transition into a more isolation-friendly model: a technical support service, maybe, to help small businesses improve their websites, create gift certificates, improve their delivery logistics, etc.

I'd want some of this to be in the form of training for small and micro-business staff; learning website design can be useful to them after this whole thing and lets them be productive in isolation. In fact, I'd do a raft of training grants so businesses could pay staff to learn

For the changes in how small businesses are conducting their operations, I'd try, if I had the bandwidth, to link them to environmental goals, maybe match with existing green economy grants where possible. I'd look for ways to make adjustments that are positive long-term changes

I'd do a special round of grants for art & cultural institutions: theaters, museums, bookstores, etc. Some would just be tide-over $$$, but also renovations, strategy, and similar improvement of online and delivery services and training for staff.

UBI: this is really common in international disaster relief, in the form of, usually, cash grants. This would be a challenging one, because of the huge and varied population. Bank transfers, checks, paypal, actual cash all have disadvantages and segments they don't work for

Anyway. basic principle is the more liquid the better (so, cash/cash equivalent > vouchers for specific things > distribution of those things) but there are exceptions (eg when affected people have nowhere to buy stuff, cash is less helpful). I might consider targeted vouchers

for parts of the economy that are going to be badly hit as we find ways to get them back online. Like (just for example) an e-voucher to everyone for books that can be redeemed at any bookstore (bookstore redeems for cash from govt). kids books, coloring books, novels, textbooks,

notebooks, pens, calendars, nonfiction, ebooks, hard copies, puzzles, games, etc. Or maybe everyone gets a voucher to get their car checked, or their hair cut, or to go to the theater or a museum, or any of above. This wouldn't replace UBI, obvs, just an extra for those sectors.

tl;dr: UBI++; provide services to help small, medium, and micro-businesses adjust; try to aim for stuff that will have long-term benefits but prioritize immediate relief; make it rain, no need to be stingy in these situations.