The research in this thesis was conducted in collaboration with Somerset NHS Foundation Trust, and the University of Exeter, during the COVID-19 pandemic. Prior to COVID-19 this research was directed at determining whether predictive models of chronic disease, developed from routinely collected clinical data, could be safely deployed into the clinical workflow. As part of this we published a novel safety framework for data driven clinical decision support. When the COVID-19 pandemic emerged, the priorities of the NHS changed, shifting towards the acute care of unwell patients. Adjusting for this, we re-oriented the research to answer the many questions about the impact of COVID-19 on the NHS. Our study on the Alpha variant was one of the earliest to show increased severity. Our identification of outbreaks of the Delta variant, and its rapid growth, was at the forefront of decision making in local NHS trusts, NHS England, Public Health England, the UK Health Security Agency, and ultimately the UK Government. As we move forward from the acute phase of the pandemic, understanding the longer term impact on chronic health management, and as a co-morbidity for chronic disease will become more of a priority for the NHS. A continued collaboration between the University of Exeter, Somerset NHS Foundation Trust and the UK Health Security Agency is well placed to address this need.EPSRC