A study team has been conducting preliminary trials on a new Ebola vaccine that incorporates a replication-defective recombinant chimpanzee adenovirus (cAd3) as a vector. Researchers have produced a bivalent vaccine (against Ebola Zaire and Ebola Sudan) and a monovalent vaccine (against the currently circulating Ebola Zaire), both being evaluated in phase 1/1B clinical trials around the world. So far, clinical data show significant efficacy 5 weeks after a single injection and partial efficacy after 10 months. In all, the data suggest the vaccine's safety and immunogenicity after a single dose. Only two out of the twenty participants in this study experienced side effects to the vaccination, which presented as transient fever one day after inoculation; both cases were linked to vaccines of higher titers.