Data collection
FLU
Immunisation programme data were collected by providers of childhood flu school vaccination on a PHE template spreadsheet. Providers submitted school-level data throughout the 2016/17 flu season and the data used was submitted as part of usual practice. No individual-level data or personal identifiable information were collected by the study team.Data on characteristics of the schools were obtained from the publicly available ‘Compare school and college performance’ UK government website.