Boosterability of Live Attenuated Japanese Encephalitis (JE) Vaccine in Children Who Have Previously Received Inactivated JE Vaccine
Condition: Japanese Encephalitis
MeSH terms: Encephalitis, Japanese; Encephalitis
Study type: Interventional
Phase: Phase 4

Summary: 
      To facilitate introduction of live attenuated SA 14-14-2 Japanese encephalitis vaccine (LJEV)
      into the National Immunization Programme of Sri Lanka, we evaluated the safety and
      immunogenicity of co-administration of LJEV and measles vaccine in children at 2 and 5 years
      of age. The primary hypothesis was that the seropositivity rate at 28 days post vaccination
      of SA 14-14-2 in subjects 2 and 5 years of age who have already received at least two doses
      of mouse brain-derived inactivated JE vaccine is greater than 80%.

      Japanese encephalitis virus is the leading cause of viral neurological disease and disability
      in Asia. The severity of sequelae, together with the volume of cases, make JE the most
      important cause of viral encephalitis in the world. Approximately 3 billion people-including
      700 million children-live in areas at risk in Asia for JE. JE most commonly infects children
      between the ages of 1 and 15 years, and can also infect adults in areas where the virus is
      newly introduced. More than 50,000 cases are reported annually and cause an estimated 10,000
      to 15,000 deaths. This figure is believed to represent only a small proportion of the disease
      burden that actually exists.
    

Detailed description: 
      JE virus is an arbovirus that causes a devastating neurological disease resulting in high
      rates of mortality or neurologic sequelae. The severity of sequelae, together with the volume
      of cases, makes JE an important cause of encephalitis. The disease is endemic across
      temperate and tropical zones of Asia,and because of its zoonotic cycle, eradicating JE from
      the environment is unrealistic. Universal childhood vaccination is essential for disease
      control.

      Concern in Japan over a rare but potentially dangerous adverse event associated with a mouse
      brain-derived vaccine led the manufacturer in Japan to discontinue production in 2005, thus
      limiting global supply of inactivated JE vaccines and raising costs for remaining inactivated
      vaccines. In August of 2006, the World Health Organization stated in its position paper on
      Japanese encephalitis vaccines that the mouse brain-derived vaccine should be replaced by a
      new generation of JE vaccines.

      In Sri Lanka, immunization against JE began in 1988. By 2006, two types of JE vaccines were
      available for use in Sri Lanka-inactivated mouse brain-derived vaccine and live attenuated
      SA-14-14-2 JE vaccine (LJEV). Only the inactivated vaccine was being used in the country's
      public-sector immunization program. It is given to children in 3 doses, at 12 months of age,
      13 months of age, and 2 years of age. A booster dose must also be given to children at 5
      years of age. If Sri Lanka decides to replace the inactivated JE vaccine with the live
      attenuated JE vaccine, there will be many children who still need a 3rd or booster dose of
      the inactivated JE vaccine. This research study was done to see if the live attenuated
      vaccine would work well to replace the inactivated JE vaccine and if it is safe in Sri Lankan
      children. The study was conducted in three peri-urban health divisions of low JE endemicity
      in the District of Colombo.
    

Intervention name(s): Live, Attenuated Japanese Encephalitis SA 14-14-2 Vaccine (LJEV)
Intervention type(s): Biological
Intervention description(s): Manufactured by Chengdu Institute of Biological Products (CDIBP), Chengdu, China; batch 200611A078-1. Administered subcutaneously in the right upper arm using 23 gauge needles.
Allocation: Non-Randomized
Intervention model: Single Group Assignment
Masking: None (Open Label)
Primary purpose: Prevention