About sixty-five people in Kenya contracted HIV while taking the preventive drugs popularly known as pre-exposure prophylaxis (Prep).
Nam-Aidsmap, a UK-based charity, in its analysis of the findings said some could have acquired HIV during a period of poor adherence or drug supply interruption since the drugs provide 100 per cent protection against HIV if taken as prescribed.
Kenya became the first African country to roll out Prep as a national programme in the public sector in May 2017.
The last count done in Kenya in 2019 showed that 25,000 people were using Prep.
However, medical experts say there is no consistent data on the number of people using Prep since a significant number takes it only to get into risky and unprotected sex.
The 65 cases are from records of between 2017 and 2021 with the ministry of Health but there could be more people who have become infected and were not documented.
The authors said most of the people who turned positive had drug resistance mutations to the Prep drugs Emtricitabine and Tenofovir, and this was higher than seen in the general population.
“The high frequency of HIV drug resistance in HIV-infected individuals on PrEP exceed background levels,” the study says. A similar survey was also conducted in Zimbabwe, Eswatini, and South Africa.
Some 79 Prep users in South Africa turned positive within the same period, 36 in Zimbabwe and 28 in Eswatini.
All the infections came from among an estimated 104,000 people taking Prep in the four countries since 2017.
Principal researcher Dr Urvi Parikh of Pittsburgh University said 35 per cent acquired HIV in the first three months on Prep, 40 per cent from three months to a year on it, and 18 per cent in people who had taken it for more than a year.
“But it does suggest that HIV infection on Prep is proving to be rare,” Nam-Aidsmap, a UK-based charity said in an analysis of the study.
The Prep users who turned positive were also tested for Prep drug levels in their blood but this showed high drug levels, indicating good adherence.
The participants who provided a blood sample for analysis had a median age of 24 years, from a range of 16 to 67 years and 74 per cent were female.
Key populations included HIV serodiscordant couples (21 per cent), female sex workers (10 per cent), men who have sex with men (9 per cent), and transgender individuals (6 per cent).
With hundreds of thousands of individuals using PrEP worldwide, only six cases have so far documented HIV infection among those with high adherence.