it's interesting in the case of immunisations, which generally have a negative 5 year cost of QUALYs are used, JCVI only considers healthcare costs not societal. Hence some of its strange decisions of a global HC QUALY approach is used.
Things may have changed, but the cost of chickenpox to the NHS is very small so a low key introduction of immunisation has been adopted. But the cost in terms of lost schooling, Lost parental work etc. is not considered as far as I can tell!