Singapore - With three new Ebola cases confirmed in Mbandaka, a city of about 1.5M people, Congo is beginning to vaccinate against the hemorrhagic virus.

The World Health Organization, which called the risk of the disease spreading "very high," is sending the country 7,540 doses of the vaccine developed by Merck.

It's also in talks about a second vaccine made by Johnson & Johnson.

According to WHO, a total of 45 Ebola virus disease cases have been reported in the DRC, including 25 deaths from April 4 through May 17. Three healthcare workers were also among 25 deaths.

This is the DRC’s ninth Ebola outbreak since the discovery of the virus in the country in 1976.

EVD, formerly known as Ebola hemorrhagic fever, is a severe, often fatal illness in humans. The virus is transmitted to people from wild animals and spreads in the human population through human-to-human transmission.