Risk Factors for Varicella Susceptibility Among Refugees to Toronto, Canada.

Several outbreaks of varicella have occurred among refugees. We aimed to estimate the prevalence of varicella susceptibility among refugees, and identify risk factors for varicella susceptibility. All refugees rostered at Crossroads Clinic in Toronto, Canada in 2011-2014 were included in our study. Varicella serology was assessed at the initial visit. Refugees' age, sex, education, time since arrival, and climate and population density of birth country were abstracted from the chart. Multivariate logistic regression was used to identify risk factors for varicella susceptibility. 1063 refugees were rostered at Crossroads Clinic during the study; 7.9 % (95 % CI 6.1, 9.7) were susceptible to varicella. Tropical climate (OR 3.20, 95 % CI 1.53, 6.69) and younger age (ORper year of age 0.92, 95 % CI 0.88-0.96) were associated with increased varicella susceptibility. These risk factors for varicella susceptibility should be taken into account to maximize the cost-effectiveness of varicella prevention strategies among refugees.