Impact of a three-dose diphtheria outbreak response immunization in East Java, Indonesia, 6 months after completion

Several outbreaks of diphtheria have occured in the East Java Province of Indonesia since 2011. The last effort to stop the outbreak in the province was a three round outbreak response immunization (ORI) in 2018.The aim of the this study was to evaluate the impact of the 2018 ORI in East Java province – 6 months following the completion of the program. Surveillance data was collected for 6 month period, from January to June 2019. The source of data was the district health offices, hospitals, community health centers, and private physician and paramedic practices. The data included demographic characteristics, involved health facilities, patient immunization history, clinical signs and symptoms, some laboratory test results and other additional examinations. All cases were evaluated by the East Java Provincial Diphtheria Expert Committee and not based on the individual physician decision. During the 6 month period, there were 97 diphtheria cases which approved by the Diphtheria Expert Committee. The reports came from 36 of 38 districts. One patient died, denoting a case fatality rate of 1%. The majority were 19 years of age or less, with uncomplete immunization. Patients above 19 years were 24%. Compared with 2017 (438 cases) and 2018 (310), 2019 saw a significant reduction in the number of reported cases. Only 4 positive culture results were collected (positivity rate 4,13%). Two patients had Mitis subtype and the other two had Gravis subtype. Diphtheria ORI in East Java had a significant impact during the first 6 months of 2019.