An interesting thought experiment but I would suspect that there needs to be some additional fact pattern there before you could show liability: knowledge that some employees had recently travelled to hot spots or were symptomatic, the meeting was in violation of official public health directives, etc.

Honestly, getting sick is out of your control and you should get paid as normal while staying at home and sickening it out; not offering this makes people go to work when sick, making other people sick, and causing much higher financial damage to the company.

I mean sure, most people have no problems muscling through a cold, but there may be others who will be floored by it for longer, or spread it to their families, etc. Is you not missing a day of work worth more to your employer than someone else missing a week? Or their life in the case of corona.

Maybe, if you can prove that you caught it at that event.

Different states have different statues, many (maybe most?) exclude communicable diseases. Even in states without that restriction you’d be burdened by showing the disease came from someone at work. On the other hand if you could show negligence on behalf of an employer facilitating the spread of COVID19 massive lawsuits would mediate the shutdown of the U.S. economy.

Given that this is a pandemic, and Trump is very interested in winning re-election in the fall, I suspect money will become available to keep people solvent if they get sick. (Plus he said exactly that yesterday in his news conference)