This document discusses cost effectiveness analysis as a tool used by the NHS to determine which health interventions provide the best value for money given limited resources. It explains that cost effectiveness analysis compares the costs of an intervention to the health benefits gained, measured in quality-adjusted life years (QALYs). The NHS currently considers interventions costing £20,000 or less per QALY gained to be cost effective. The analysis found the Bexsero meningitis vaccine to have a cost per QALY above £20,000, so the JCVI could not initially recommend it for routine use, though some argue the model underestimated disease burden.