No .5 means nothing was found circulating in the blood. The number is a chemical artifact of the test.
The reason we were concerned was because of the range of non-reactivity which is from 0 to 2. We thought that if the result was 0 then that mean no surface antigen in the blood whatsoever- meaning never been exposed. However, 0.5 we thought meant that there were some particles circulating in the blood.
I see. Thank you very much.
the 0.5 is simply a background result. It means surface antigen was not detected with this test and NOT that just a tiny amount was detected.