Children of the 90s and some other UK longitudinal studies have been approached directly by Sir Patrick Vallance and Sir Chris Whitty to help with understanding the nature of Long-COVID. This is part of the National Core Studies for COVID research that Children of the 90s is playing a major role in. The NHS and government planners need evidence to inform UK NHS strategies for managing this new and complex condition. At this stage the NHS planners are concerned that it is not clear who has Long COVID and if the national data they are working with properly represents the scale of this new and poorly understood condition. In this project we will compare the data of consenting Children of the 90s participants who have reported having Long-COVID with English GP records to determine the level of agreement between the two. If not all Children of the 90s participants can be identified from the GP records alone as having Long-COVID then this may indicate that national estimates of how many people have these symptoms/outcomes may be inaccurate and the scale of the challenge is under-estimated. This will help identify if new GP coding practice is needed, and to determine how best to help people with this form of COVID.