ESTIMATING THE IMPACT OF UNIVERSAL VARICELLA VACCINATION IN JORDAN

• Published in: Value in health 2017-05, Vol.20 (5), p.A85
• Main Authors: Daniels, V, Hayajneh, WA, Weiss, TJ, Pillsbury, M, Kyle, J, Wolfson, LJ
• Format: Article
• Language: English
• Subjects: Adults; Age composition; Age differences; Age distribution; Chicken pox; Epidemiology; Immunization; Infants; Infections; Mortality; Older people; Prevention programs; Public health; Sensitivity analysis; Serology; Vaccination; Varicella
• ISSN: 1098-3015; 1524-4733
• DOI: 10.1016/j.jval.2017.05.005

OBJECTIVES: More than 50% of the Levant population has access to universal varicella vaccination (UW). In order to avoid changes in the age-distribution of varicella cases, and significantly reduce disease burden, it is important for other countries in the region to consider UW. The objective of this study is to assess the magnitude of current varicella disease burden and the potential impact of UW in Jordan. METHODS: A dynamic transmission model of varicella infection was calibrated to available varicella seroprevalence data within the region and validated against local epidemiological data. The current burden was assessed by converting the calibration into age-specific incidence and mortality rates, and the impact of one-dose UW administered at 12 months of age with 90% coverage (concurrent with MMR vaccination which as >95% coverage) was estimated. Alternative vaccination strategies were examined as sensitivity analyses. RESULTS: The model estimates the current burden of varicella to be 188,000 cases per year, an incidence rate of 2,475/100,000 persons. Varicella incidence is projected to decrease by 38% at 1 year, 79% at 5 years, 86% at 10 years, and 90% at 25 years. After 5 years of UW, 743,000 cases and 93 deaths due to varicella will be prevented; over a 25 year period, more than 4 million cases and 500 deaths due to varicella will be prevented. Importantly, the public health benefits extend beyond vaccinees, with a 92% disease reduction in unvaccinated infants and an 84% reduction in unvaccinated adults. At low coverage levels (10%), such as might be seen with private-sector only varicella vaccination, slight shifts in the age-distribution of cases to older adults are likely. CONCLUSIONS: UW in Jordan will significantly reduce varicella disease burden and protect against possible age-shifts in varicella case distribution that could be caused by synergies of private-sector only vaccination and high UW rates within the region.