Almost all people living with HIV now start the same first-line regimen, but outcomes on that regimen vary. Some remain virally suppressed, some experience rebound and later resuppress, and a minority develop resistance mutations that reduce the number of effective treatment options available to them. Resistance genotyping can identify which mutations are present and which drugs are likely to remain active, and in well-resourced health systems a baseline genotype is often obtained before treatment begins. After treatment has started, however, genotyping is usually repeated only once viral rebound has been detected. It is therefore used mainly to guide management after failure, rather than to identify in advance who is at increased risk of developing resistance.

As a result, decisions about who may need closer monitoring, earlier switching, or an alternative regimen are generally made without an individual estimate of resistance risk. This is particularly important because resistance testing is concentrated in high-income settings, whereas treatment failure is common in settings where genotyping is limited and viral load monitoring may be intermittent. A prediction strategy that depends on genotype may therefore be least accessible in the settings where it could be most useful.

The student will use mathematical modelling, clinical data and genomic sequences to address the problem.