D.C.
Under § 32-1501 (12) of the DC Code, “Injury” is defined as an “accidental injury or death arising out of and in the course of employment, and such occupational disease or infection as arises naturally out of such employment or as naturally or unavoidably results from such accidental injury, and includes an injury caused by the willful act of third persons directed against an employee because of his employment.” (Emphasis added). Unless the person who contracts the disease is a researcher working with the virus (which would arise naturally out of the employment), the ordinary employee exposed to the virus at work would not fall within the definition of an infection that naturally arises out of the employment.
There are a couple of older administrative level decisions finding that enhanced physiologic reactions from work exposure which are a temporary aggravation of an underlying condition are not compensable because they are only temporary. By analogy, if symptoms from COVID-19 are only temporary, they would not be compensable either (and probably not in the case of a researcher). In addition, even if compensable, the claimant would have to prove the exposure occurred in the workplace and not out in the general public.
The bottom line is that COVID-19 exposure in the workplace in DC is not compensable.