Socio-economic factors predicting drop-out of paediatric HIV prevention programming among adolescent mothers in South Africa

撒哈拉以南非洲是全世界艾滋病毒感染率和少女意外怀孕率最高的地区，少女和青年妇女在这两项挑战中承受着最大的社会经济和健康后果。南非是全球艾滋病毒感染者人数最多的国家，由于年龄差异、性交易和亲密伴侣暴力等若干社会、关系和生物风险因素，青少年妇女仍占所有新感染者的近三分之一。控制艾滋病毒流行的关键是预防母婴传播，因为这会对母亲、其子女和整个社会造成若干不利的健康和社会经济后果。在南非，未成年母亲的母婴传播率比成年人高出三倍，这使她们成为预防方案干预的关键但往往被忽视的优先人群。因此，迫切需要了解南非青少年及其婴儿在何处、何时和为何退出预防母婴传播服务，以及在何处可以改善这些服务，以最终消除儿童艾滋病毒感染。拟议的DPhil研究旨在通过量化COVID-19发病前后青少年母亲在PMTCT计划中的保留率来回答这些问题，并确定哪些社会经济因素预测儿科艾滋病毒预防效果不佳。为此，研究将利用来自南非东开普省一个大型多波青少年母亲及其子女队列的数据，这些青少年母亲及其子女参加了HEY BABY纵向研究（开普敦大学和牛津大学之间的一项研究合作）。该数据在三个方面具有独特性：i）包含超过1000对母子，两者的数据都有关联; ii）其纵向性质，跨越COVID-19大流行病爆发前后的三波;以及iii）多个数据来源，包括每个母子的自我报告访谈、患者档案和医学实验室记录。这些丰富的数据允许使用更先进的统计方法，包括边际效应建模、分类和回归树分析、人口归因分数分析和路径分析结构方程建模，所有这些都将用于确定预防母婴传播规划的哪些阶段应该改进，以及哪些可修改的社会经济因素对儿科艾滋病毒结果影响最大。这将提供基于证据的政策和规划指导，确定政府和资助者可以有效优先投资和干预工作的关键领域。

Sub-Saharan Africa has the highest rates of both HIV infection and unintended adolescent pregnancy worldwide; two challenges in which adolescent girls and young women bear the greatest socio-economic and health consequences. In South Africa, which is home to the largest population of people living with HIV globally, adolescent women still account for nearly a third of all new infections, due to several social, relational, and biological risk factors such as age-disparate relationships, transactional sex, and intimate partner violence. Critical to the control of the HIV epidemic is the prevention of mother-to-child transmission (PMTCT), as this causes several adverse health and socio-economic outcomes for mothers, their children, and society more broadly. Adolescent mothers in South Africa have up to three times higher rates of mother-to-child transmission compared to adults, making them a critical, yet often overlooked, priority population for prevention programming intervention. Thus, there exists an urgent need to understand where, when, and why South African adolescents and their babies drop out of PMTCT services, and where these services can be improved to ultimately eliminate paediatric HIV infection. The proposed DPhil research aims to answer these questions by quantifying retention in PMTCT programming among adolescent mothers pre- and post-COVID-19-onset, and determining which socio-economic factors predict poor paediatric HIV prevention outcomes. To this end, the research will draw upon data from a large, multi-wave cohort of adolescent mothers and their children living in the Eastern Cape Province, South Africa, enrolled in the HEY BABY longitudinal study (a research collaboration between the Universities of Cape Town and Oxford). This data is unique in three ways: i) the inclusion of over 1000 mother-child pairs, with linked data for both, ii) its longitudinal nature, spanning three waves pre- and post-onset of the COVID-19 pandemic, and iii) multiple data sources, including self-report interviews, patient files, and medical laboratory records for each mother-child pair. This rich data allows for the use of more advanced statistical methodology, including marginal effects modelling, classification and regression tree analysis, population attributable fraction analysis, and path analysis structural equation modelling, all of which will be employed to determine which stages of PMTCT programming should be improved, and which modifiable socio-economic factors have the most significant impact on paediatric HIV outcomes. This will provide evidence-based policy and programming guidance, identifying key areas where government and funders can effectively prioritise their investments and intervention efforts.