Gem is an epidemiologist with a PhD in Public Health. Her research interests include topics related to the public health approach to treating HIV in Southern Africa, including describing long-term trends in the characteristics and treatment outcomes among people with HIV receiving treatment. Her areas of research have included the implementation of differentiated service delivery models of care, CD4 and viral load monitoring strategies for antiretroviral therapy programmes and more recently, advanced HIV disease and treatment failure in the era of widespread access to antiretroviral therapy, with a particular focus on treatment options for paediatric and adolescent populations.