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 World Health Organisation, which is deploying vaccines to the country, previously expressed its concerns of the disease reaching the city of Mbandaka.
She says health experts have identified 500 contacts who are now being traced.
"Five thousand four hundred doses of vaccine arrived from Geneva this morning" said health ministry spokeswoman Jessica Ilunga.
Authorities said they were tracing all air, river, and road routes in and out of the city to find the source of the virus.
Until now, all the confirmed Ebola cases were reported from Bikoro health zone, which is also in Equateur Province but at a distance of almost 150 km from Mbandaka.More news: Carrie Underwood Returns to 'American Idol' as a Mentor, Performs 'Cry Pretty'
This is the ninth time that the DRC has been dealing with the Ebola epidemic since 1976.
The Ministry of Health of the Democratic Republic of the Congo announced the finding, after laboratory tests conducted by the Institut National de Recherche Biomédicale (INRB) confirmed one specimen as positive for EVD. As per Associate Press, Congo's health minister has confirmed that Ebola has spread to the capital of Equateur province.
The vaccine, developed by Merck and Co Inc, is still not licensed but proved effective during limited trials in West Africa in the biggest-ever outbreak of Ebola, which killed 11,300 people in Guinea, Liberia and Sierra Leone from 2014 to 2016.
Out of the 20 persons died in DRC, 3 are health workers, Director of the Center John Nkengasong said.
Before the latest confirmed case, Peter Salama, the WHO's deputy director-general for emergency preparedness and response, said the current number of suspected, probable or confirmed cases stood at 42, with 23 deaths attributed to the outbreak.