The U.N.'s health agency has begun vaccination for the Ebola virus in the Democratic Republic of the Congo after an alarming outbreak killed at least 26 people, the agency's chief said yesterday.

"I am pleased to say that vaccination is starting as we speak," World Health Organization (WHO) Director-General Dr. Tedros Adhanom Ghebreyesus told the opening of WHO's six-day annual assembly in Geneva, as reported by Anadolu Agency (AA).

The first phase unfolded in Mbandaka yesterday, followed on Saturday in Bikoro, about 150 kilometers (90 miles) away. Donors have promised 300,000 doses of the vaccine, a government spokesman said, of which around 5,400 have already been received. WHO has dispatched 35 immunization experts, including 16 mobilized during the last deadly outbreak in West Africa that occurred in 2013. The rest of the team is made up of newly trained Congolese staff.

The WHO's previous leadership was heavily criticized for its slow response to the outbreak that was declared in March 2014 and continued until January 2016, killing over 11,300 people. It was later found to have begun in late 2013, but the WHO did not call an emergency meeting until August 2014. This time the WHO has moved rapidly to mobilize the response, convening an Emergency Committee and sending a vaccine to ring-fence the outbreak and stop it spreading further. The latest outbreak is Congo's ninth since the disease made its first known appearance near the vast central African country's northern Ebola River in the 1970s. It was named after a Congolese river where the first cases were recorded.