Kenya appears to be in a relatively safer position when it comes to HIV drug resistance, thanks to its widespread use of tenofovir-based treatment regimens, new research has found.

A study published last week in Clinical Infectious Diseases has revealed that resistance to dolutegravir (DTG), the cornerstone of Kenya’s first-line HIV therapy, is far less likely to develop when combined with tenofovir compared to older drugs like zidovudine or abacavir.

DTG is highly effective and has a strong barrier to resistance. However, if taken alone, HIV can still mutate and become resistant. For this reason, the World Health Organization recommends that DTG always be paired with at least two additional drugs from a different class.

The multi-country study analysed 660 patients in Kenya, South Africa, and other regions. Among 183 patients with ongoing detectable virus, 11.5% showed resistance to dolutegravir.

Crucially, patients on zidovudine were nearly 20 times more likely to develop resistance compared to those on tenofovir, while those on abacavir were five times more likely to show resistance.

“Our multi-cohort analysis suggests that HIV genotypic dolutegravir resistance is more common when dolutegravir + lamivudine is co-administered with either zidovudine or abacavir compared to tenofovir,” the authors reported.

The difference lies in the “half-life”, how long a drug remains active in the body. Dolutegravir binds to HIV for over 70 hours, while tenofovir’s active form persists in cells for several days. In contrast, abacavir and zidovudine wear off much faster. When patients miss doses, dolutegravir can end up working alone, giving HIV a chance to adapt and develop resistance.

Kenya adopted dolutegravir in 2019 as part of the TLD combination (tenofovir + lamivudine + dolutegravir) as the national first-line treatment for adults and adolescents. According to the Ministry of Health’s 2022 HIV guidelines, TLD remains the preferred regimen for most patients.

However, the picture is different for children under 30 kg, who are usually placed on an abacavir-based regimen (ABC/3TC/DTG). Tenofovir is not recommended for this group because of risks to bone and kidney health, leaving children more vulnerable to drug resistance. In cases where abacavir is not tolerated, zidovudine, which also carries higher resistance risk, is used as a substitute.

Globally, HIV drug resistance has disrupted treatment programmes before, forcing mass changes in therapy. Dolutegravir was hailed as a breakthrough because resistance was expected to remain rare. This new evidence challenges that assumption, at least in some settings.

Drug resistance has severe consequences, as it forces patients to switch to more expensive and less widely available second- or third-line treatments. For children, early resistance can limit their options for life, potentially leaving them dependent on difficult-to-tolerate regimens well before adulthood.

Some Kenyan healthcare workers told The Star that resistance remains rare but warned that limited access to Drug Susceptibility Testing (DST) leaves many cases undetected.

“The problem is we still do not do DST to check if the virus is resistant to certain drugs. When we do a case summary for referral to Kemri, we are given a Nat number but told there are no reagents for testing,” said one nurse.

The study underscores the need for routine resistance monitoring and continued investment in drug availability to protect Kenya’s gains in the fight against HIV.