The country's Health Minister Oly Ilunga Kalenga stated late on Wednesday that the nation's Ebola outbreak had now entered a "new phase".
The WHO is anxious about the disease reaching the city of Mbandaka with a population of about 1 million people, which would make the outbreak far harder to tackle.
"We will intensify the monitoring and tracing of the population to all air, sea and road access routes".
At least 44 suspected cases have been registered since the beginning of the epidemic with 23 deaths including 1 confirmed Ebola death, according to the latest statistics from the Minister of Health. As per the report, epidemiologists are working to identify additional contacts to the 500 already identified.
Senior World Health Organization (WHO) official, Peter Salama, said the spread to Mbandaka meant there was the potential for an "explosive increase" in cases.
It is the ninth time Ebola has been recorded in DRCongo since the disease made its first known appearance near its northern Ebola river in the 1970s.
Ebola is most feared for the internal and external bleeding it can cause in victims owing to damage done to blood vessels.
"In our experience, for each confirmed case of Ebola there are about 100-150 contacts and contacts of contacts eligible for vaccination", Jasarevic said.
Spokeswoman Jessica Ilunga says the vaccines will be sent to Mbandaka and Bikoro, the rural areas where two confirmed cases and several suspected cases have been reported.
Thousands of doses of an experimental Ebola vaccine arrived in Congo's capital this week, the health ministry said Wednesday.
Over 11,000 people have died of Ebola in Liberia, Guinea and Sierra Leone between 2014 and 2016. The health body also sent 300 body bags for safe burials in affected communities.