Follow CDC guidelines. Symptoms may include fever, coughing, and shortness of breath. This will have to be determined on a company by company basis. Some companies say if they have a persistent or difficult to control cough they will not be allowed on site. Some companies will not let them even approach their Wellness Checkpoint if they have symptoms.
These symptoms can mimic other health issues as well, such as allergies. No matter what we recommended that you error on the side of safety.