A Phase I/II Trial of Tetravalent Live Attenuated Dengue Vaccine in Flavivirus Antibody Naive Infants

Dengue Clinical Trial

Official title: A Phase I/II Trial of Tetravalent Live Attenuated Dengue Vaccine in Flavivirus Antibody Naive Infants

Status Completed

Clinical Trial Summary

The main target populations for the tetravalent live attenuated dengue virus vaccine are indigenous populations, especially infants less than 2 years old, residing in areas of the world endemic for dengue and at risk of developing dengue hemorrhagic fever (DHF). The presence of maternal dengue antibody during the first year of life makes it unlikely that a vaccine given during that time will have long-term efficacy, as the vaccine virus would likely be neutralized prior to necessary replication. Children older than 18 months may have preexisting flavivirus antibody. Therefore, vaccination of infants living in Thailand early in the second year of life (between the ages of 12 and 18 months) seems most beneficial. The aim of this trial is to evaluate the safety and immunogenicity of a two-dose schedule of a tetravalent live attenuated dengue vaccine in flavivirus antibody naïve infants beginning at 12-15 months of age.

• To assess the kinetics of dengue neutralizing antibodies to each dengue virus serotype one and four years following dose 2 of dengue/control vaccination in the setting of potential wild-type dengue virus exposure.

• To assess the immunogenicity, the safety and reactogenicity of a booster dose of dengue vaccine administered at Year 3 following primary vaccination.

Clinical Trial Description

• This is a Phase I/II, randomized, observer-blind, controlled trial. Thirty-four flavivirus naïve infants will be randomized to the vaccine group and 17 infants to the control group.

• Infants receive dengue vaccine at study months 0 and 6 or control vaccine (Varicella vaccine at study month 0 and Haemophilus influenzae Type b Conjugate vaccine at study month 6). Both are licensed for use in Thailand.

• All infants subsequently receive an inactivated JE vaccine approximately one and 1.5 months following dengue vaccine dose 2.

• Infants are monitored daily for 21 days following each dengue or control vaccination and 7 days after each JE vaccination for solicited adverse events. Unsolicited events will be recorded up to 31 days (days 0-30) after dengue/control vaccinations and each day after dose 1 of JE vaccine until the concluding study visit.

• Study duration (excluding screening) is approximately 8.5 months for each subject.

• Each enrollee is followed a four year period following dose 2 of dengue/control vaccination to assess for dengue-related hospitalizations and dengue antibody kinetics.

• Investigators will administer a 3rd dose of tetravalent dengue vaccine to all subjects who received 2 doses of dengue vaccine (0 and 6 months) during the primary phase of the study. The 3rd dose will be administered 3 years following the primary vaccination series. Peripheral blood mononuclear cells (PBMCs) and sera will be collected at the time of dose 3, and twice again at one month and one year following dose 3 from dengue group subjects.

Investigators will address the following questions:

1. Is a 3rd dose of live virus tetravalent dengue vaccine safe in Thai toddlers/children?

2. Is a 3rd dose of live virus tetravalent dengue vaccine required in toddlers/children to induce optimal immune (neutralizing antibody, cellular mediated immunity) responses?

3. Is there evidence of T and B cell memory following a primary dengue vaccination series (dose 1 and 2)?

4. How does a 3rd dose of live virus tetravalent dengue vaccine impact B and T cell memory? ;

Related Conditions & MeSH terms

• Dengue

• NCT number: NCT00322049
• Study type: Interventional
• Source: U.S. Army Medical Research and Materiel Command
• Status: Completed
• Phase: Phase 1/Phase 2
• Start date: February 2004
• Completion date: June 2009