GlaxoSmithKline's (GSK) Ebola vaccine has been shipped to Liberia for first large-scale trials.Trials of the vaccine, which uses a type of chimpanzee cold virus, are expected to begin as early as next week.GSK said it hopes to enrol 30,000 people following the shipment of the first dose to Monrovia.While the vaccine has been developed quickly, the number of cases of Ebola has declined in Liberia with only eight cases in the country last week, according to the World Health Organisation on Thursday.The vaccine is the first of several under development to enter trials in west Africa.Dr Moncef Slaoui, chairman of global vaccines at GSK, said: "The initial phase I data we have seen are encouraging and give us confidence to progress to the next phases of clinical testing, which will involve the vaccination of thousands of volunteers, including frontline healthcare workers. If the candidate vaccine is able to protect these people, as we hope it will, it could significantly contribute to efforts to bring this epidemic under control and prevent future outbreaks."It is important to remember that this vaccine is still in development and any potential future use in mass vaccination campaigns will depend on whether the WHO [World Health Organisation], regulators and other stakeholders are satisfied that the vaccine candidate provides protection against Ebola without causing significant side-effects and how quickly large quantities of vaccine can be made."