Varicella Trends in Kuwait; A Successful Control

Introduction: Varicella Vaccines introduced in 2017 nationally mandating two doses regimen at age of 1 and 2 years old.Aim: Analysis to explore trends in varicella incidence and changes in case characteristics before and after the implementation of varicella vaccination policy.Method: This study was an observational ecological study design with a retrospective secondary analysis of reported varicella cases from January 2011 to December 2022.Cases were analyzed according to Vaccine introduction in the following two time periods: 2011-2017 "pre-vaccine" and 2018-2022 "post-vaccine".Results: Varicella infection used to be very high in Kuwait; the annual reported incidence rate reached more than from 250/ 100,000 population peaking during the May and June.Incidence was slightly greater for males than females (M:F ratio 1.2) and cases among Non-Kuwaitis were more than Kuwaitis.The number of reported varicella cases declined (-74.7%) during the 5 years following the introduction of Varicella Vaccination.Cases declined in all age groups (62% -84%), but the greatest decline was observed in the target age group 1-4 years (-84.1%).Declines observed among the non-targeted population including infants (-78.2%),adolescents and adults (-70.5%)not eligible for vaccination indicating the effect of herd immunity during post-vaccination period.Admission to infectious diseases hospital reflecting severity of cases dropped by -97% from 47.3 in 2011 to 3.4 in 2022 per 100,000 population.Nationality specific incidence rate was higher among Kuwaitis although the number of cases was higher among non-Kuwaitis.Conclusion: A study over a 15-year span shed light on Varicella infection epidemiology and the impact of vaccination on disease trends.It is important in developing vaccination strategies and other public health measures to minimize the healthcare and economic impact.