The first doses of the Ebola vaccine were sent to West Africa and are expected to arrive today, according to a spokesperson from GlaxoSmithKline (GSK), one of the companies that has created the vaccine with the National Institutes of Health.

“Shipping the vaccine today is a major achievement and shows that we remain on track with the accelerated development of our candidate Ebola vaccine,” Dr. Moncef Slaoui, chairman of global vaccines at GSK said in a company release.

A variation of the vaccine from Merck and NewLink will also be tested.

The trial of the vaccine made by Merck and NewLink was temporarily stopped in December after some of the volunteers in the trial experienced joint pain. No similar side effects were noted in the GSK trial.

This first shipment will be used in the first large-scale trial in the next few weeks in Liberia.

“We are expecting to start by the last week in January, but there are some details that need to be ironed out regarding the FDA,” said Dr. Anthony Fauci, the director of the National Institute of Allergy and Infectious Diseases (NIAID) at a press conference.

Since the outbreak started in December 2013, there has been an estimated 21,759 infections and at least 8,668 people have died from Ebola.