OBJECTIVES

: In Switzerland, a 2-dose catch-up vaccination is recommended for those who are unvaccinated or haven’t contracted varicella by age 11-15 years. A small but increasing minority of children are being privately vaccinated against varicella with 2 doses. This study assessed the impact of increasing varicella vaccination coverage in infants (9-12 months) on clinical and economic outcomes in the Swiss setting.

METHODS

: A dynamic transmission model was used to simulate different vaccination strategies from the payer perspective. Ten two-dose strategies with different coverage rates were evaluated, from 0%-0% to 95%-90% (maximum coverage) for the 1^st dose at 9 months and 2^nd dose at 12 months respectively. The proportion of eligible adolescents who received catch-up doses was set to 68% (first catch-up dose) and 35% (second catch-up dose). The time horizon was 50 years.

RESULTS

: As coverage increased from 0%-0% to maximum, the number of varicella cases decreased from 6,051,475 to 665,418 (89.0% decrease) over 50 years. However, incidence (per 100,000) in the 15+ age group increased from 67 with 0%-0% to 286 with 80-85% before falling to 117 at maximum coverage. The number of hospitalizations increased from 17,634 with 0%-0% to 26,546 with 50%-50% (50.5% increase) before falling to 9,030 at maximum coverage (66.0% decrease). Deaths initially increased 6.2% from 119 to 127 (from 0%-0% to 50-50% coverage) before falling to 61 (51.6% reduction at maximum coverage).

CONCLUSIONS

: Higher vaccination coverage was associated with a decrease in disease burden in terms of lower incidence of varicella cases. Low to medium-level varicella vaccination in the private market may increase varicella incidence in those aged over 15 and may have indirect effects on morbidity and mortality in more vulnerable older population. Hence, given increasing private sector use of varicella vaccines, universal varicella vaccination strategies with high coverage should be considered in Switzerland.