The study will be carried out to provide supportive clinical data on the feasibility, efficacy, safety, and PK of LPV based therapies in routine treatment setting and will be based on the existing LPV/r pellets which already represent a clear advantage in comparison with the liquid formulation.

The primary objective is to evaluate the effectiveness of LPV/r pellets in addition to AZT/3TC (or ABC/3TC) paediatric fixed dose combination (FDCs) tablet under routine treatment conditions in HIV infected infants and young children who cannot swallow tablets.

As secondary objectives:

• Document the safety of LPV/r pellets and AZT/3TC or ABC/3TC
• Assess the population pharmacokinetics of LPV/r and NRTIs when administered as LPV/r pellets plus AZT/3TC or ABC/3TC
• Measure adherence to the new formulation
• Evaluate children acceptability of the LPV/r pellets and associated dual NRTIs as well as ease of use by the care giver.

Inclusion Criteria:

• Past or current documentation of a confirmed diagnosis of HIV infection defined as two positive assays from two different samples taken at a different date as preferred option.

• At any age: HIV-1 DNA PCR positivity
• At any time >4 weeks of age: HIV-1 p24 antigen detection or HIV-1 RNA viral load > 5,000 copies/mL plasma
• At any age >18 months: HIV-1 antibody reactive on two different manufacturers' licensed rapid tests based on a different antigen preparation and/or different test principal, or repeatedly reactive on a licensed enzyme immune assay (EIA)and confirmed on a second sample by any one of the following assays: rapid test (a third manufacturer), licensed EIA, Western blot, chemi-luminescence assay, or plasma RNA with a viral load > 5,000 copies/mL

One single positive PCR assay result will be acceptable for inclusion of a child less than 18 months in the study Although the 2nd PCR assay would not be performed at the time of treatment initiation/treatment switch,

• In case the test is RNA PCR viral load), the sample should be taken before treatment initiation and analyzed as soon as possible thereafter,

• In case the child is already on treatment, the test should be DNA PCR based, the blood sample can be taken while on treatment and the results be made available as soon as possible.

• ARV treatment eligible children with LPV-based treatment indication* as defined by country-specific guidelines or the WHO pediatric treatment guidelines confirmed by investigator:

  1. ARV naïve, or
  2. Already on first line liquid lopinavir based treatment, or
  3. Failing first line NNRTI based therapy

• Weight ≥3 and <25 kg at the time of enrolment.

• Inability to swallow tablets*

• Parent or legal guardian able and willing to provide written informed consent. *Age is not an inclusion criterion. Children older than 5 years who need a LPV/r based treatment and cannot swallow tablets are eligible. Analysis will be stratified according to study entry point (naïve, first line, failure)

Exclusion criteria

• Planned or concurrent use of NNRTIs, integrase inhibitors, entry inhibitors, or PIs other than LPV/r.
• PIs treatment failure with the presence or strong suspicion of a PI resistance mutation.
• Clinical condition requiring the use of a prohibited medication in association with LPV/r
• Any clinically significant disease or finding during screening that, in the investigator's opinion, would compromise participation in this study.