The cost-effectiveness of introducing a varicella vaccine to the New Zealand immunisation schedule

This study examined the cost-effectiveness of adding a varicella vaccine to an existing, childhood immunisation schedule relative to a counterfactual where the varicella vaccine is available on a user-pays basis (the current New Zealand situation). The costs and consequences of chickenpox in an annu al cohort of 57,200, ii-month old children were simulated for a 30-year per iod. The cohort simulation design captures the 'phasing-in' effects of rout ine varicella vaccination on the population. From a health care payer's perspective (medical costs only) every dollar in vested in a vaccination programme would return NZ $0,67, However, from a so cietal point of view (which includes the value of work-loss), a vaccination programme would return NZ $2,79 for every dollar invested. To implement a varicella vaccination programme covering 80% of 15-month old children in Ne w Zealand would add more than NZ $1 million in net direct (health care) cos ts each year. However, the indirect cost savings from reduced losses of wor k-time exceed NZ $2 million annually. The net average health care cost per child vaccinated over the 30-year mode lling period was $54 whereas the cost-savings from work-loss averted averag ed $101 per child vaccinated. Total cost-savings to society of $47 per chil d vaccinated, on average, could be gained from a vaccination programme. The finding that the addition to vaccination costs resulting from a routine programme (including the cost of complications from the vaccine) were grea ter than the offsetting health cart: cost savings from reduced incidence of chickenpox were robust to a sensitivity analysis on all assumptions within plausible ranges. Overall cost-effectiveness estimates were most sensitive to assumptions regarding lost work-time, the discount rate, and the price and efficacy of the vaccine. Estimates were relatively insensitive to chang es in assumptions regarding health care utilisation. (C) 1999 Elsevier Scie nce Ltd. All rights reserved.