IMMUNOGENICITY OF LIVE ATTENUATED SA14-14-2 JAPANESE ENCEPHALITIS VACCINE - A COMPARISON OF 1-MONTH AND 3-MONTH IMMUNIZATION SCHEDULES

Live attenuated SA14-14-2 Japanese encephalitis (JE) vaccine has been safe and effective in > 100 million immunized children, but its curren t administration schedule of two doses given a year apart does not len d itself to inclusion in established Expanded Program of Immunization (EPI) schedules of childhood immunization. Immune responses to immuniz ation at shorter intervals were compared in middle-school-aged childre n immunized with two doses separated by 1 month (n = 116) or 2.5 month s (n = 115), Two vaccine lots were compared, Seroconversion to the vac cine was observed in 100% of vaccinees immunized in the 1-month schedu le and in 94% (lot 2) and 100% (lot 1) of vaccinees immunized in the 2 .5-month schedule, Geometric mean titers were almost 2-fold higher wit h the longer schedule, The routine administration of JE SA14-14-2 vacc ine to infants in an EPI schedule should be possible using either inte rval.