(CNN)After months racing not only to treat Ebola but to find ways to prevent it, health authorities will launch a vaccination campaign Saturday in one of the areas that has been most devastated by the disease. The trial, using vaccines developed by the Public Health Agency of Canada, will be administered in Basse Guinee, a region that has had the highest number of Ebola cases in Guinea. Another vaccine will be tested in a subsequent study, according to a press release from the World Health Organization, Medecins Sans Frontieres (Doctors Without Borders), and the Norwegian Institute of Public Health. "We have worked hard to reach this point," WHO Director-General Dr. Margaret Chan said. "... If a vaccine is found effective, it will be the first preventive tool against Ebola in history." Patient Zero -- i.e. the first case in the current Ebola outbreak -- is thought to be a 2-year-old Guinean boy who contracted the virus in December 2013 and died a few days later. Since then, the vast majority of the more than 23,900 cases and more than 9,800 deaths reported by WHO have come in Guinea and neighboring Liberia and Sierra Leone. There are new Ebola cases every day, including 132 in the last week of February (which is up from 99 reported the previous week). While Liberia didn't have any of these new incidences, Guinea did -- especially in Forecariah and Conakry. Still, authorities in Africa and their partners around the world have had significant successes generally in combating the deadly disease. The progress -- as measured in the rate of new cases, with January's incidences being the lowest in seven months -- has been so significant that health authorities' focus has shifted from slowing the spread to ending the epidemic. This positive movement has come as a result of steps like better disease control, public awareness campaigns and attention to burial practices. But the tool that has been used to eradicate many other contagious diseases -- vaccines -- has been elusive. That's why, over the past six months, WHO has been working with scientists, ethicists and policymakers to try to create both better treatment therapies and a vaccine that will stop people for getting Ebola in the first place. Health workers in the Guinea trial will start with a new Ebola case and then trace all of that patient's contacts, giving each of them the option of getting vaccinated. John-Arne Rottingen, from the Norwegian Institute of Public Health, said this program is happening at the request of Guinean authorities and called the participation of residents there "vital" to its success. "The Ebola epidemic shows signs of receding but we cannot let our guard down until we reach zero cases," WHO official Marie-Paule Kieny said. "An effective vaccine to control current flare-ups could be the game-changer to finally end this epidemic and an insurance policy for any future ones."
WHO leader: This vaccine could be "the first preventive tool against Ebola in history"
This trial campaign will be conducted in a hard-hit region of the West African nation of Guinea . Authorities have had success in curbing Ebola, but dozens of new cases still arise each week .