Boosterability of Live Attenuated Japanese Encephalitis (JE) Vaccine in Children Who Have Previously Received Inactivated JE Vaccine

Japanese Encephalitis Clinical Trial

Official title: Assessment of the Immunogenicity and Safety of Japanese Encephalitis Live Attenuated SA 14-14-2 Vaccine in Children in Sri Lanka

Status Completed

Clinical Trial 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.

Clinical Trial 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. ;

Related Conditions & MeSH terms

• Encephalitis
• Encephalitis, Japanese
• Japanese Encephalitis

• NCT number: NCT00463476
• Study type: Interventional
• Source: PATH
• Status: Completed
• Phase: Phase 4
• Start date: July 9, 2007
• Completion date: October 2, 2008