Epidemiological Impact of Universal Varicella Vaccination on Consecutive Emergency Department Visits for Varicella and Its Cost-Effectiveness Among Children

Abstract

Varicella is highly contagious and endemic worldwide. Previous studies reported a dramatic decline in varicella incidence and varicella-related deaths after implementing universal varicella vaccination (VarV). However, its impact and cost-effectiveness remain unknown in single emergency department (ED). We retrospectively reviewed the clinical database of consecutive patients younger than 16 years presenting to our primary ED between January 1, 2011, and December 31, 2019. Of the 265,191 children presenting to our ED, 3,092 were clinically diagnosed with varicella. The annual number of varicella patients was approximately 500 before introduction of the universal two-dose VarV in October 2014, and it decreased to approximately 200 in 2019. The number of varicella patients younger than 1 year (not eligible for vaccination) also decreased. Regarding the cost-effectiveness of VarV, approximately JPY1.5 million (US$14,300) were saved annually by our center. However, our study showed a relatively large percentage of infected unvaccinated children presenting to our ED (59.0%). After implementation of the universal VarV, infection was mainly observed in older children (i.e., the unvaccinated generation). In conclusion, our data showed excellent universal VarV effectiveness and cost-effectiveness in the ED. Additionally, our data suggest that the VarV should be administered to all eligible older patients.