In the United States, you can sue anyone for anything. Winning is another matter. That being said, it’s unlikely you’ll be sued for exposing someone to coronavirus because, in most cases, it’s hard to identify exactly who infected who.
To successfully sue a business, the person would likely have to prove intentional exposure that was the proximate cause of the infection. Let’s say you have a customer who self-quarantines at home but for some reason visits only your business. You’ve been diagnosed with the coronavirus but take no precautions while dealing with the public. You even cough a few times in the customer’s face (and there are witnesses). In that scenario, the customer might win a lawsuit if infected.