Effectiveness of the SA 14-14-2 Live-Attenuated Japanese Encephalitis Vaccine in Myanmar

Myanmar is an endemic country for the Japanese encephalitis virus (JEV), and the SA-14-14-2 live-attenuated JEV vaccine was first introduced as a catch-up vaccination campaign in 2017. To determine the effectiveness of vaccination by means of neutralizing antibody titers against JEV, a cross-sectional descriptive study was conducted among five to 15-year-old monastic school children in Mandalay, Myanmar. A total of 198 students who had received vaccines were recruited, and single-time investigation of anti-JEV IgG and neutralizing antibodies against wild-type JEV were determined using anti-JEV IgG ELISA and plaque reduction neutralization tests (PRNT50). All students 100% (198/198) showed positive results on the anti-JEV IgG ELISA, and 87% (172/198) of the students had neutralizing antibodies against JEV six months after immunization. The geometric mean titers of both IgG antibodies and neutralizing antibodies increased with the participants' age groups, and statistically significant differences in anti-JEV IgG titers were noted across age groups. In this study, we could not investigate the persistence of neutralizing antibodies as only single-time blood collection was done. This study, which is the first report of JEV vaccination among children in Myanmar, showed similar neutralizing antibody production rates among vaccinated individuals as did studies in other countries.