Up until January this year, only two people were ever reported cured of HIV/AIDS. And now, researchers have said there may be a third case -- an African American woman, who was diagnosed with HIV in 2013, and started on anti-retroviral therapy. In 2017, she was diagnosed with leukaemia and received embryonic stem cells, in the form of cord blood, from a donor who had a rare mutation that naturally blocks HIV from infecting the body’s cells. She also received adult blood stem cells from a relative. Now, doctors say, the woman shows no signs of HIV in her blood and has no detectable antibodies either, making the 60-year-old woman possibly the third case of a person who has been cured of the virus -- the other two cases, both men, received bone marrow transplants as well, from donors with the rare mutation. Unlike the other two cases, however, the woman did not develop graft vs host disease -- a condition where the donor stem cells attack the recipient. Could this be because of the use of embryonic stem cells with adult stem cells? Her doctors believe this may possibly be a factor. Stem cell therapy, exciting as it is in the field of medicine, is not accessible or possible in the case of a vast majority of persons living with HIV/AIDS in the world. Anti-retroviral therapy or ART, however, has ensured that those with access to the medicines now have long lifespans, comparable to those without HIV/AIDS. A vaccine against the virus would be an ideal solution, offering a potential cure, but close to 40 years since researchers first began to study it, the world still does not have a vaccine for this virus, though there are recent reports of a potential vaccine based on the mRNA platform. In India, as of 2019, an estimated 23.48 lakh people live with HIV/AIDS -- the prevalence among adult males is estimated at 0.24% of the population and among adult females, the prevalence is 0.20%. Worldwide, over 37 million people live with HIV/AIDS. So what is the potential stem cell ‘cure’ all about? What is the rare mutation that naturally blocks HIV from entering cells? Why is a vaccine so hard to make, and does the mRNA platform, first used for a COVID-19 vaccine, offer hope? Guest: Dr Akhil C Banerjea, emeritus professor, National Institute of Immunology and former director, Institute of Advanced Virology, Kerala Host: Zubeda Hamid Edited by Reenu Cyriac