Dear Dr. Little: I was diagnosed HIV+ in 1995, am treatment naive, and have been in good health since then. My CD4 count is 594 and viral load is 3,849. Here's my question; I've been invited to participate in a clinical trial at a major research hospital in which I will be given AZT monotherapy in directly observed therapy for 21 days and I am interested in your opinion as to the possible future consequences this might cause to my immune system and possible cross resistance to other HAART meds. The goal of the study is to evaluate the lowest effective dose of AZT. After the 21 day period the AZT would be discontinued. I'd like to participate for two reasons; it seems it might help others and I could use the money! Thanks very much.

I think that the risk is low (not zero) that a 21 day course of AZT would result in drug resistance. If you have never received any antiretroviral drug therapy, the risk is actually quite low. The problem is only that I cannot say the risk is zero. This means that you need to balance the personal benefit with the personal risk and make sure the risk is justified for you.