I visited a barbershop in India which are not hygienic. I had a pimple on the head near my ear and the barber cut me by razor. It had bled and he then wiped the blood with cotton. After that, I had done antibody test after 103 days which was negative. We usually call a nurse who comes to our home and collects blood. I am concerned about the method of his blood collection. The nurse first injected the needle and then put the blood in the jar and after 15 seconds,he put the lid on the jar. I am concerned that in that 15 seconds, air might have entered the jar and could it possibly give any error in the result of the test?