For most of us our first encounter with Ebola was in 2014 when an epidemic hit West Africa (Guinea, Sierra Leone and Liberia). This was the most widespread outbreak of the virus in its recorded history. It took nearly two and a half years for all three countries to be declared Ebola-free from the first discovered case, and resulted in 28,600 cases and 11,325 deaths. During this period the pharmaceutical Merck began a clinical trial with their experimental vaccine in Guinea. Their field tests in Guinea in 2016 showed a 100% success rate in preventing the transmission of Ebola in those people who were vaccinated vs a population who did not receive the vaccine. The vaccine is most effective against a strain of Ebola called 'Ebola-Zaire' which is thought to be the same strain currently being transmitted in the Democratic Republic of Congo (DRC).

Despite not being authorised for use by any country, the DRC government has approved it's use under their compassionate-use regulations. The Vaccine Alliance have purchased 300,000 doses of the vaccine and have already sent 4,000 doses to the DRC, with a further 5,000+ vaccines due to arrive within the next few days. They plan to use a method called ring vaccination to target potential high-risk patients. This method works by observing the people who have had contact with any infected individual. The theory behind this is to form a buffer of immune individuals between a naive population and the infected individual to prevent the further spread of disease. This method was used to control smallpox right up until its last active case in 1977, leading to its eventual eradication in 1980.

The main differences between this outbreak and the epidemic of 2014 is firstly, there is a proven vaccine; secondly, the mobilisation of health care workers and the government to isolate and control infected areas has been faster; thirdly, international travel and trade restrictions were in place quicker and finally the knowledge that all bodies involved have from the previous outbreak to better understand how to control and prevent further spreading of the disease.

Despite all of these advantages there are still key obstacles which need to be overcome in order to bring this outbreak under control. 

1. The disease has reached an urban area, Mbandaka, with a population of 1.2million people as well as close proximity to the Congo river which has a lot of traffic which have the potential to cross many borders into neighbouring countries 

2. The remote location of most of the current cases makes it difficult for health workers to reach the infected individuals and set up surveillance to implement the ring vaccination strategy

3. The countries poor infrastructure means there are frequent power outages, making the storage of the vaccines more difficult. They have to be stored at between -60°C and -80°C, and when in convoy can only be stored at normal refrigerated temperatures for up to two weeks

4. As the vaccine is not an authorised product they will need translators with the health care workers to gain signed permission for each person to be inoculated 

With the first vaccines due to be administered today to health workers the further spread of the disease will need to be tracked closely, as well as observing the success rate of uptake for the vaccine. Over the next few weeks if the disease fails to be brought under control we could see the disease starting to move further afield.