Monitoring progress towards the elimination of measles in Iran: Supporting evidence from 2014 to 2016 by application of measles outbreaks data

Abstract

Background: To achieve the goal of measles eradication, all WHO member countries should continuously monitor the status of measles elimination. This work aims to characterize measles outbreaks in Iran from 2014 to 2016 and calculate the effective reproduction number, given that the country has recently eliminated measles. Methods: Effective Reproduction Number (R) was estimated to achieve the goal of measles elimination using measles related outbreaks data and epidemiological data from the cases linked to imported cases. Three methods were used to estimate R includes (i) proportion of cases imported, (ii) distribution of outbreak size and (iii) distribution of outbreak generations. Results: Of the 153 outbreaks occurring during the three years of the study, 29 outbreaks (19%) were unknown source, 86% of them were single cases. Estimates of R during the study period by proportion of cases imported were 0.79 (95% CI: 0.73-0.86). Corresponding values for distribution of outbreak size and distribution of outbreak generations methods were R = 0.83 (95% CI: 0.68-0.97) and R = 0.76 (95% CI: 0.54-0.90), respectively. Conclusions: Estimated values of R represent the important achievement that the outbreaks of measles originating from the indigenous genotype in Iran have been eliminated. Moreover, Iran has also achieved the goal of measles elimination by end of 2015.