OBJECTIVES

: Varicella (chickenpox) is caused by primary infection of the varicella zoster virus. It is a highly contagious disease and most people are infected as children. At the age of 12, only 3% are susceptible in Sweden. After primary infection, the virus can be reactivated later in life and cause herpes zoster (shingles). The aim was to assess cost-effectiveness of including varicella vaccine to children and herpes zoster vaccine to elderly in the Swedish vaccination program, by comparing health-effects and costs with a vaccination program versus no vaccination program.

METHODS

: We developed a dynamic transmission model to simulate the burden of varicella and herpes zoster in the Swedish population, accounting for indirect effects of vaccination (herd-immunity). The main outcome was number of individuals with varicella and herpes zoster. The model was calibrated to fit Swedish data. Costs included in the analysis were those incurred when treating varicella and herpes zoster, production losses during sick-leave or when caring for a sick child, and acquisition and administration of two vaccines. Health effects were measured as quality-adjusted life years. The time horizon was set to 100 years. Both health effects and costs were discounted by 3% annually, and were accumulated over the time horizon to create an incremental cost-effectiveness ratio.

RESULTS

: Preliminary results show that vaccination is likely to be cost-effective. The shingles incidence would increase in the short term, whilst the incidence of varicella would decrease – both due to direct effects among vaccinated as well as through herd-immunity. This has an effect on the cost-effectiveness, since the cost of implementing the program occur immediately, whilst some if the benefit occur in the future.

CONCLUSIONS

: The cost-effectiveness of the vaccines are highly dependent on price of the vaccine, and the level of discounting, since many of the benefits of a program occur in the future.