Understanding rare exceptions to the 6 month seroconversion window

Question

Dear Doctors: Having followed discussion on this forum for some time, it appears

that there are a large number of people who are concerned about exceptions to the

general 6-month seroconversion window period. You have done a wonderful job of trying

to balance the reality that almost everyone who is infected

will test positive by 6 months with the possibility that some persons--probably quite

small in number, if not infintesimal relative to the former group--may take longer than

6 months. I am wondering if one way to lend further clarity to this issue and to ease

people's minds is to provide any information about the reasons why some people

do in fact take longer than 6 months. For example, I have heard/read that most documented

cases in which people took longer than 6 months involved instances in which other factors were

also at work: impaired immune systems due to chemotherapy; aggamaglobulinemia; prolonged

IV drug use; etc... Do you have any information from the literature or from your own clinical

experience that speaks to this issue?

Answer

Dear Six Month Window questioner,

You are right, it is the odd case that takes longer than 6 months following exposure to "seroconvert" or have their HIV antibody test turn positive. It usually is because there is some other reason why the person can't make the antibody, like chemotherapy, steroid use, drugs, but in some cases (extremely rare), that is just the way it is. If you factor in the overall relatively low risk that some of the people that worry about this have, then couple that with the very small chance of being infected with a negative test at 6 months, the overall risk is so low, it is impossible to calculate.

RM