Immunogenicity, immune persistence, and safety of japanese encephalitis vaccine schedules among adults in Ningxia, China.

Live attenuated and vero-cell-inactivated Japanese Encephalitis vaccines (LJEV, IJEV) have been in common use in young children in China since 1989 and 2004, associated with large reductions in Japanese encephalitis (JE) incidence. In 2013, northern China reported JE outbreaks among adults born before JE vaccine availability, a trend that worsened in 2017-2018. We conducted an open-label, randomized, controlled trial (ChiCTR2500103235) to assess the immunogenicity, immune persistence, and safety of three JE vaccine schedules in 40-69-year-olds to provide evidence for adult targeted JE immunization efforts. Outcomes were seroconversion proportions and seropositive prevalences; adverse events were monitored. The vaccines were immunogenic with no significant difference between vaccination groups. Seropositivity remained above 80% at one year post-vaccination. No serious adverse events occurred. All three schedules had good, persistent immunogenicity and favorable safety profiles in 40-69-year-old adults, providing evidence supporting vaccinating adults in response to the emergence of adult JE in northern China.