Hi there, I had never heard of Ozone therapy before but I have just had a quick read on the Internet about it and it seems that this method of treatment is fairly controversial and under researched. Upon reading about Ozone therapy and its effects on HIV, I do not believe that enough has been scientifically proven as to whether antibodies to HIV would be delayed or destroyed. "According to one 2005 report, there is not enough evidence to recommend ozone therapy for HIV or other infectious diseases, heart disease, cancers, skin conditions, or a range of other conditions. Although ozone has shown success against the virus that causes HIV outside the body, no research to date has shown its safety or effectiveness in live humans." https://www.medicalnewstoday.com/articles/320759#does-it-work Given that there is not enough evidence in relation to the effects of Ozone therapy and HIV infection, I am confident in saying that your negative result at 15 weeks is reliable and you do not need to retest. I hope this helps. Kindest regards, Becky