Research into stem cells has paid off as 68-year-old Paul Edmonds remains effectively cured of both HIV and leukemia following treatment that included a breakthrough stem cell transplant in 2019. Now, five years after the treatment, Edmonds continues to live his life free of HIV and leukemia.

This makes Edmonds one of only five people in the world who have achieved full remission of HIV. Further, his 31 years of living with the virus also means he had it the longest out of the five in remission. It’s a striking accomplishment that he has remained in remission for so long and showcases just how effective these kinds of treatments can be.

Stem cell transplants aren’t a new idea, either. What particularly makes this treatment so effective and intriguing, though, is that the transplant donor had a rare genetic mutation called homozygous CCR5 delta 32. This mutation makes people immune to most types of HIV.