All patients will be prescribed treatment drugs in accordance with the national protocol by the doctors of the AIDS centers. The decision to prescribe Doravirine will also be made by doctors.

Doravirine will be given to patients after failure on the first NNRTI regimen.

The result of measuring the HIV viral load 8 weeks after the start of DOR-based treatment. The success of therapy will correspond to an undetectable level of viral load (less than 50 RNA copies/ml) or a decrease of two logarithms compared with the values before treatment start. Upon receipt of a detected viral load, treatment will be nevertheless continued up to 24 weeks.

The result of measuring the HIV viral load 24 weeks after the start of DOR-based treatment. The success of therapy will correspond to an undetectable level of viral load (less than 50 RNA copies/ml). Upon receipt of any detected viral load, the treatment will be considered a failure and the reasons for the failure (lack of adherence, drug interactions, non-compliance with dietary requirements, etc.) will be analyzed. If these causes are excluded, the HIV genotype will be analyzed for the presence of drug resistance mutations (RT genome region).

HIV genotype in patients experienced failure on DOR-based treatment regimen (RT genome region). The study of the genotype will make it possible to understand to which of the components of the therapy regimen the virus has developed resistance and which of the drugs needs to be replaced. If it turns out to be a drug from the basic regimen (not DOR but NRTIs), the regimen will be changed at the discretion of the attending physician (this decision is not within the scope of this project). If DOR resistance mutations are detected such as V106I or Y188L, their frequency will be estimated (the proportion of patients with such mutations ) and the spectrum of associated mutations will be analysed.