A Model Immunization Programme to Control Japanese Encephalitis in Viet Nam

Nguyen Thu Yen, Wei Liu, Hoang Duc Hanh, Na Yoon Chang, Tran Nhu Duong, Robert V. Gibbons, Florian Marks, Nghiem Anh Thu, Nguyen Minh Hong, Jin Kyung Park, Pham Anh Tuan, Ananda Nisalak, John D. Clemens, Zhi-yi Xu

Abstract


In Viet Nam, an inactivated, mouse brain-derived vaccine for Japanese encephalitis (JE) has been givenexclusively to ≤5 years old children in 3 paediatric doses since 1997. However, JE incidence remainedhigh, especially among children aged 5-9 years. We conducted a model JE immunization programme toassess the feasibility and impact of JE vaccine administered to 1-9 year(s) children in 3 standard-dose regimen:paediatric doses for children aged <3 years and adult doses for those aged ≥3 years. Of the targetedchildren, 96.2% were immunized with ≥2 doses of the vaccine. Compared to the national immunizationprogramme, JE incidence rate declined sharply in districts with the model programme (11.32 to 0.87 per100,000 in pre- versus post-vaccination period). The rate of reduction was most significant in the 5-9 yearsage-group. We recommend a policy change to include 5-9 years old children in the catch-up immunizationcampaign and administer a 4th dose to those aged 5-9 years, who had received 3 doses of the vaccineduring the first 2-3 years of life.

Key words: Demonstration project; Effectiveness study; Immunization; Japanese encephalitis; Vaccines


Full Text: PDF