Sir I have the following question:- a) what is the risk of acquiring hiv or other blood-borne viruses through razors, trimmers, cippers, scissors etc or other barbering equipments and in what conditions can it occur? B) if a barber uses a razor with disposable blades and uses a new blade every time is that enough to prevent the risk of hiv with other things like the scissors, trimmers, clippers, razors (the holder) remaining the same and being reused and sensitisation not being carried out between customers? C) what precautionary measures can be taken while getting a haircut done to minimize the risk of hiv or other blood borne viruses like hepatitis? D) is the hiv 4th generation duo test conclusive after 45 days of suspected exposure? E) what is the window period for testing of hepatitis b and hepatitis c?