Estimating the extent of mobility among PLHIV and TB in South Africa and its effect on treatment outcomes

Adhering to HIV and tuberculosis (TB) treatment is essential for controlling both diseases, but it poses significant challenges for individuals who frequently move within and across borders in South Africa. 

We recognised that mobility among people living with HIV (PLHIV) and TB patients was disrupting their access to medication and treatment adherence, leading to poorer health outcomes. This problem also increased the risk of drug resistance and onward transmission.

We undertook a mixed-methods approach to understand the scale and nature of this issue. We conducted a comprehensive literature review and undertook key informant interviews to explore the reasons why people disengaged from HIV and TB treatment. This work uncovered important information about policy gaps, administrative hurdles, and stigma-related barriers. 

We also performed an ecological analysis using diverse data sources to estimate the number of PLHIV and people with TB who are internally and cross-border mobile leveraging data to provide by develop a nuanced understanding of mobility's characteristics and prevalence.

We identified key mobile populations, including those moving for economic opportunities - such as truck drivers, construction workers, farm workers, and sex workers - as well as students and undocumented individuals. Our estimates showed that 1.32 million PLHIV (18% of the estimated 7.3 million PLHIV in South Africa) and 79,874 TB patients (21.5% of estimated TB cases) were internally mobile. Approximately 448,107 PLHIV (6.1%) and 20,610 TB patients (0.7%) were cross-border mobile.

Mobility was a significant contributor to treatment interruptions, as patients often switched health facilities without formal transfer processes. This created "silent transfers," which inflated loss-to-follow-up rates in facility records. While South Africa's flexible antiretroviral (ART) and TB treatment guidelines existed to support mobile populations, we found they were applied inconsistently, with some clinics denying care without transfer letters. 

Furthermore, guidelines largely ignored cross-border mobility, leaving migrants vulnerable to treatment disruptions due to distrust in the health system, fear of xenophobia, and inadequate electronic referral infrastructure.

Our research provided evidence to inform policy and programme development. It highlighted that improving treatment adherence for mobile populations requires flexible transfer mechanisms, mobile treatment distribution, digitised patient records, and enhanced support for undocumented individuals. The insights gained support the national effort to ensure that mobility does not become a barrier to achieving the UNAIDS 95-95-95 targets and TB elimination goals.