Most likely, no. As an employer, you should determine whether there was any exposure that occurred in the work environment that caused or contributed to the test positive. As a practical matter, it is very difficult to do this and not practical to ascertain there was exposure on the worksite. OSHA would have to prove that the employee testing positive was work-related. If you have a COVID-19 case that results in a fatality or in-patient hospitalization, you would want to call OSHA. You would also likely be engaged with your local health department if this were to occur.