Joy has lived and worked in many African countries, including  as a lecturer and neonatalogist in Ghana in the 1990s. She shifted to public health and global estimation working at the WHO Collaborating Center, CDC Atlanta, USA (1998-2001), and then at the Institute of Child Health, London, UK (2001-2004), completing a Masters of Public Health at Emory University, Atlanta and a PhD in perinatal epidemiology at University College London, UK. For ten years she was been Director Global Evidence and Policy for Gates Foundation funded Saving Newborn Lives (SNL) programme of Save the Children, working with governments and partners to scale up and evaluate newborn care including leadership in the Every Newborn Lancet series and Action Plan.

She has published over 150 peer reviewed papers, with a combined average annual citation of 600, as well as a range of chapters, books and policy relevant reports. Since 2004, Joy has coordinated the United Nation’s Child Health Epidemiology Reference Group’s (CHERG) Neonatal Team and coordinated the GBD Expert team for neonatal and congenital conditions, co-leading several Lancet series on newborn survival and stillbirths. She is on the scientific committee of Countdown to 2015 and co-chairs the Health Systems and Policy Working Group.

She is also a founding Board Member of Powerfree Education and Technology, a South African not-for-profit organization developing and testing innovative, wind-up technology to improve maternal, newborn and child survival, which has won awards and a number of grants.