A Study to Assess the Acceptability of the Darunavir/Cobicistat (DRV/COBI) Fixed-dose Combination (FDC) Tablet in Human Immunodeficiency Virus (HIV)-1 Infected Children Aged >=3 Years and Weighing >=15 kg to <25 kg

Human immunodeficiency virus type 1 (HIV-1) infection is a life-threatening and serious disease that is of major public health interest around the world. Standard-of-care for the treatment of HIV infection involves the use of a combination of antiretroviral (ARV) drugs to suppress viral replication to below detectable limits, to increase CD4+ cell count, and to delay disease progression. Darunavir (DRV) is an inhibitor of the dimerization and of the catalytic activity of the HIV-1 protease. It selectively inhibits the cleavage of HIV encoded Gag-Pol polyproteins in virus infected cells, thereby preventing the formation of mature infectious virus particles. Cobicistat (COBI) is a mechanism-based inhibitor (MBI) of the cytochrome P450 (CYP)3A subfamily. Inhibition of CYP3A mediated metabolism by COBI enhances the systemic exposure of CYP3A substrates, such as DRV, where bioavailability is limited and half-life is shortened by CYP3A-dependent metabolism. DRV/COBI FDC tablet formulation would overcome the difficulties of pediatric participants (greater than or equal to [>=] 3 years and weighing >=15 kilograms [kg] to less than [<] 25 kg) might encounter in swallowing a whole or 2 halves of an oral, non-disintegrating tablet, hence helping children to better adhere to their HIV treatment. The study consists of a screening phase (up to 21 days) and an open-label administration phase of 1 day. Safety will be assessed by adverse events (AEs). The total duration of the study is up to 32 days.