Unravelling the risk factors and long-term health consequences of long COVID in the UK population

Despite the end of the COVID-19 pandemic in May 2023, many people continue to experience persistent or newly emerging symptoms, known as long COVID. In the United Kingdom, around 1.9 million people are affected, highlighting its ongoing public health burden. Long COVID includes more than 200 multisystem symptoms that complicate diagnosis and treatment. Neurological symptoms, often described as "brain fog", are common and overlap with early signs of Alzheimer's disease. Evidence of viral persistence and chronic immune activation suggest that long-term immune dysregulation may increase neurological risk and potentially support cancer-promoting environments. Existing studies rely on hospital-based cohorts, likely missing people with mild or moderate disease who still develop long COVID. Broader studies including both hospitalised and non-hospitalised cases are therefore needed to better understand the biological and non-biological determinants of long COVID. This thesis addresses this gap by investigating the multifactorial determinants of long COVID through integration of population-level epidemiological data, genomic analyses, and mechanistic cellular studies.