This is a prospective observational cohort study of 2820 patients on first-line ART switching to a DTG-based first-line regimen, according to the standard of care. The study is conducted in Malawi and Zambia, in ART programs that participate in the IeDEA collaboration. Sequencing will be done on blood samples of patients with a viral load above 400 copies/mL to identify mutations.

Dolutegravir (DTG), a second-generation integrase strand transfer inhibitor (InSTI), is widely used in high-income countries and is recommended by the World Health Organization (WHO) as an alternative first-line ART regimen. In countries where viral load monitoring is not routinely available many patients on first-line ART will be switched to a DTG-based regimen despite the detectable viral load, which could increase the risk of selection of resistance to DTG as the majority of patients with virologic failure on first-line EFV-based ART have NRTI mutations. The investigators hypothesize that the proportion of patients experiencing virologic failure 48 and 96 weeks after switching to a DTG-based regimen will be higher in patients who switched with virologic failure (VL>400 copies/mL) compared to patients who switched with suppressed viral replication (VL<400 copies/mL). This is a prospective observational cohort study of 2820 patients on first-line ART switching to a DTG-based first-line regimen, according to the standard of care. The study is conducted in Malawi and Zambia, in ART programs that participate in the IeDEA collaboration. At the time of switching to DTG, a baseline study assessment will be done, and a blood sample will be taken. Sequencing will be done on blood samples of patients with a viral load above 400 copies/mL to identify mutations.

Inclusion Criteria:

Patients

• On first-line ART for 6 months or longer
• Switching to any DTG-based treatment

Exclusion Criteria:

• No informed consent

People living with HIV.