My father highly likely contracted covid-19, and he's still coughing since his symptoms began three weeks ago. does it mean that he's still virulent? or is that the effect of the virus on his lungs? he already took antibotics. thank you?

There are no antibiotics that treat COVID 19 at this time. Antibiotics treat bacterial infections that can cause a superimposed infection. I am missing details,- does he have chest symptoms? After a lung infection, it may take several weeks for a cough to resolve in order for the lungs to heal. Although, ongoing infections can continue a cough. So, he needs to be seen by a doctor in person

His cough may be a result of reactivity of the airway and airway inflammation. If he has a wet cough, antibiotics may be considered since the cough is prolonged. A sputum sample may be helpful in determining the treatment. COVID-19 has also been associated with prolonged respiratory symptoms. A follow up with your physician is recommended. Watch for shortness of breath, fever and green sputum.