Effectiveness of the Viet Nam Produced,Mouse Brain-Derived,Inactivated Japanese Encephalitis Vaccine in Northern Viet Nam

Background: japanese encephalitis (je) is a flaviviral disease of public health concern in many parts of asia. je often occurs in large epidemics,has a high case-fatality ratio and,among survivors,frequently causes persistent neurological sequelae and mental disabilities. in 1997,the vietnamese government initiated immunization campaigns targeting all children aged 1-5 years. three doses of a locally-produced,mouse brain-derived,inactivated je vaccine (mbv) were given. this study aims at evaluating the effectiveness of viet nam's mbv. methodology: a matched case-control study was conducted in northern viet nam. cases were identified through an ongoing hospital-based surveillance. each case was matched to four healthy controls for age,gender,and neighborhood. the vaccination history was ascertained through je immunization logbooks maintained at local health centers. principal findings: thirty cases and 120 controls were enrolled. the effectiveness of the je vaccine was 92.9% [95% ci: 66.6-98.5]. confounding effects of other risk variables were not observed. conclusions: our results strongly suggest that the locally-produced je-mbv given to 1-5 years old vietnamese children was efficacious. © 2012 marks et al.