The number of children exposed to HIV and possibly to antiretroviral therapy (ART) in utero and during breastfeeding and are uninfected (HEU) globally will continue to increase from the estimated 15.9 million in 2021. There are still significant gaps in our understanding of the impact of HIV and/or ART exposure in children who are HEU, in terms of prevalence/incidence and severity on health and wellbeing, and long after exposure has ended. While there have been substantial programmatic efforts to support the elimination of vertical transmission of HIV, additional rigorous research is needed to better understand the biological, (psycho)social and structural factors contributing to optimal health for populations who are HEU. Furthermore, the best approaches to address and study the gaps in understanding also need to be explored. Given the scope of the problem including the large numbers of affected people as well as the often limited and competing in-country resources for populations affected by HIV, novel methodologies, including multi-level approaches and advanced analytics, need to be considered. A growing population of children who are HEU are maturing into adolescence and young adulthood. Research to advance understanding of the possible negative long-term effects of HIV and/or ART exposure in these youth is supported by the US National Institutes of Health. Both large epidemiological studies and smaller more comprehensive cohort studies may be required to address the complexity of the issue. Integrating both types of studies could allow the establishment of more reliable and validated predictions of which youth who are HEU are at the highest risk for specific negative health outcomes, such as mental health and neurocognitive disorders, and which interventional approaches may be most successful to address specific deficits both in terms of prevention and treatment. Finally, these goals can be more rapidly achieved with data science efforts, data harmonisation between studies and with sustainable data-sharing practices. It is important to expand the commitment to research to identify biological, social and structural drivers, to develop screening tools, and impactful and contextually appropriate interventions to address the health and wellbeing of children who are HEU from birth through adulthood.