Parts of Uganda's western border are not far from areas within DR Congo where the Ebola outbreak is being contained.
Concerns that an undiagnosed Ebola patient may arrive at a health facility seeking treatment led to the decision to vaccinate health care workers at the highest risk of contracting the highly-infectious hemorrhagic fever, in 40 facilities near the border.
It was learned from authorities that about 26,000 people in the central African country have meanwhile received a vaccine to prevent Ebola.
The lack of security has complicated efforts to contain the Ebola outbreak as humanitarian workers helping to fight the outbreak have come under attack by armed groups.
More deaths have been recorded in the Ebola outbreak in the eastern Democratic Republic of Congo, claiming more than 180 lives.
This particular vaccine is now being administered in DRC and is demonstrating positive protective results and potency against the Ebola virus-Zaire type.
As such, a total of 2100 doses of the Ebola vaccine will be administered to frontline health workers in Uganda under expanded or compassionate use.
In Congo, where thousands of people have been given the experimental Ebola vaccine, a worrying number of vaccinated health workers have been infected.
Since the latest outbreak started in August, there have been 305 reported cases of Ebola in Congo's Ituri and North Kivu provinces, according to the WHO.
Health officials in DR Congo are battling the outbreak which continues to kill many.
The deteriorating security situation in the DRC has complicated efforts to get the Ebola outbreak under control: across the country, local populations and humanitarian workers assisting them have come under attacks by armed groups, necessitating the deployment of a large United Nations peacekeeping mission.
Investigators believe that the first victim of Ebola in any outbreak acquires the virus after coming into contact with a "reservoir" animal, say an infected bat or monkey.
It is the tenth outbreak of Ebola in the country, then called Zaire, where the disease was first detected in 1976. These red flags include that half of the outbreak cases have occurred in the past month, a total of 28 health care workers have been infected, contact tracing is becoming hard because of violence in the region, and that community members are dying from Ebola infection before being diagnosed.
The current Ebola outbreak in DRC is the country's second in 2017.