Thomas Kahlert, the man known as the “second Berlin patient”, has remained free of HIV for eight years without treatment after a stem-cell transplant, but his case offers no treatment option for people living with the virus in Ghana.
Kahlert, 62, received cells from an unrelated female donor on 14 October 2015, after being diagnosed with acute myeloid leukaemia. He stopped taking antiretroviral medicines in September 2018, a decision his doctors say he made himself.
Researchers had not expected the transplant to work because the donor did not have the genetic protection associated with most previous HIV cures. Kahlert has worked at Berlin’s Charite university hospital for 38 years and said he was doing “very well” when speaking to German news agency dpa at the opening of BeCURE, the hospital’s new HIV cure research centre.
His HIV was discovered during a routine check-up in 2009. The Ghana AIDS Commission says too few men in Ghana are undergoing comparable testing.
Why Kahlert’s case is unusual
HIV mainly enters immune cells through a receptor known as CCR5. A rare mutation, CCR5-delta32, disables that receptor, and people who inherit two copies are considered naturally resistant to HIV.
The mutation is found most often in northern Europe, where up to about 16 per cent of copies of the gene carry it, but is almost absent in sub-Saharan Africa. Timothy Ray Brown, the first Berlin patient, became the first person known to have been cured after receiving leukaemia treatment in Berlin with cells from a donor carrying two copies of the mutation.
Several later cases also involved donors with the double mutation. Kahlert’s donor had only one copy, which does not provide the same protection. Kahlert has nonetheless remained free of detectable HIV.
His case was published this year in Nature by a Charite team led by Christian Gaebler, Samad Kor and Olaf Penack. Repeated tests found no intact virus in his blood, while no virus was grown from more than 130 million of his CD4 immune cells. Tests on tissue from his gut also found no HIV.
The researchers believe the donor’s immune system may have destroyed cells containing hidden virus, an effect they call graft-versus-reservoir. However, they say the mechanism remains unconfirmed and describe the result as “durable HIV remission and potential cure”, rather than a confirmed cure in a single patient.
Stem-cell transplants in these cases were performed to treat cancers such as leukaemia and lymphoma, not HIV. amfAR describes them as high-risk procedures that are “only an option for a very small number of people with both HIV and certain blood cancers”.
For others, antiretroviral therapy remains the treatment. Ghana has provided it since 2003, helping drive a continued fall in AIDS-related deaths, according to the Ghana AIDS Commission’s latest estimates.
dpa reports Kahlert is one of 13 people worldwide considered cured of HIV, while UNAIDS says 1.2 million people acquired the virus in 2025. amfAR lists 13 people cured or in possible long-term remission after stem-cell transplants, although several are considered likely or potential cures. In one case in Chicago, HIV returned after treatment stopped; only the Geneva patient also received cells without the mutation, and amfAR says it remains unclear whether he has been cured. Brown died in September 2020 after his leukaemia returned.
Ghana recorded 13,951 new infections in 2025, down from 15,290 the previous year. Greater Accra had the highest number, at 3,141, while more than 18,000 children are estimated to be living with HIV.
The Food and Drugs Authority warned herbal producers in October against unproven claims to cure serious diseases, while the AIDS Commission urged journalists in August to report HIV accurately and without stigma. Medicine supplies have also faced pressure: in July the Commission said new antiretroviral medicines and test kits were weeks away, and in August the government cleared donor-funded supplies held at Tema port.
Kahlert’s medical history will be used by BeCURE researchers to help develop new treatment methods.
