A Booster Dose of Ad5-EBOV in Healthy Adults After Primary Immunization

Since its first outbreak occurred in 1976, Zaire Ebola virus have been associated with 14 outbreaks reported up to 2014. The Zaire Ebola virus in 2014 causing the most serious outbreak was considered to be a new epidemic strain, with GP homology of the gene was only 97.6%, compared to the GP gene of the strain in 1976. This investigational Ad5-EBOV vaccine was developed according to the 2014 epidemic Zaire strain and formulated as freeze-dry products which could be stored at 4℃. In 2014, a single center, double-blind, placebo control, dose-escalation phase 1 clinical trial was performed in Taizhou, China. Our findings show that the Ad5-EBOV vaccine is safe and robustly immunogenic. One shot of the high dose vaccine could mount glycoprotein-specific humoral and T-cell response against Ebola virus in 14 days. The investigators intent to evaluate the safety and immunogenicity of a booster dose of the recombinant Ebola adenovirus vector vaccine (Ad5-EBOV) in healthy adults after primary immunization in this add in study. The investigators expect that the boosting immunization with a same vaccine for primary immunization is possible and could confer a longer-lived protection when needed. The phase I trial has been unblind 28 days after the primary vaccination, but all the subjects are still kept blind as well as the laboratory staffs. Therefore, this booster vaccination trial will be conduct in single blind.