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

Adherence to HIV and tuberculosis (TB) treatment is critical for disease control but can be challenging, particularly for mobile individuals who move within and across borders. Mobility amongst people living with HIV (PLHIV) and TB in South Africa disrupts not only access to medication but also treatment adherence, increasing the risk of poor health outcomes.

We employed a mixed-methods approach, combining a comprehensive literature review, key informant interviews, and secondary data analysis. Through literature reviews and key informant interviews, we explored why individuals disengage from HIV and TB treatment, uncovering critical insights on policy gaps, administrative burdens, and stigma-related barriers. Through an ecological analysis, we estimated the number of PLHIV and people with TB who are internally and cross-border mobile. By leveraging diverse data sources, our team developed a nuanced understanding of the prevalence and characteristics of mobility. These findings provide crucial evidence to inform policy improvements, ensuring that health systems are better equipped to support mobile populations and improve treatment adherence.

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

Mobility significantly contributes to treatment interruptions, as patients often switch facilities without formal transfer processes, leading to "silent transfers" and inflated loss-to-follow-up rates. Existing interventions, such as South Africa's flexible antiretroviral (ART) and TB treatment guidelines, aim to support mobile populations but are inconsistently applied, with some clinics denying care without transfer letters. Additionally, cross-border mobility remains largely unaddressed in guidelines, leaving migrants vulnerable to treatment disruptions due to distrust in the health system, fear of xenophobia, and inadequate infrastructure for electronic referrals.

This represents a notable amount of PLHIV and people with TB in the country, therefore, improving treatment adherence for mobile populations requires flexible transfer mechanisms, mobile treatment distribution, digitised patient records, and enhanced support for undocumented individuals. Our research provides critical insights to inform policy and programme development, ensuring that mobility is not a barrier to achieving the UNAIDS 95-95-95 targets and TB elimination goals.