Congo's health ministry says another Ebola case has been confirmed as the pace of new cases slows one month after the outbreak was officially declared.
The ministry also reported five new suspected cases on Thursday, including two in Mbandaka, a city of 1.5 million people.
Ebola is back. The disease that killed more than 11,000 people in West Africa just a few years ago has returned, striking the Democratic Republic of the Congo (DRC).
Archbishop Fridolin Ambongo Besungu, co-adjutor archbishop of Kinshasa who previously served in the Diocese of Mbandaka-Bikoro, where the outbreak occurred, chose to suspend administering sacraments to protect churchgoers from contracting the disease.
Beginning with the 1976 discovery of Ebola in an area that is now the Democratic Republic of Congo, the country has experienced nine outbreaks.
It is the capital of Equateur province, where the small town of Bikoro also is located.
"It's extremely likely the vaccine has had a positive effect", said Salama, basing his assessment on the fact that in Mbandaka there have been no confirmed cases since mid-May and a large portion of contacts have been vaccinated there.
"We have added cause for optimism because now we have reached... more than 98 percent of the contacts with vaccination", Salama said.
He said the focus now was on rural isolated communities in the Iboko health zone which would present logistical and other challenges.
On the front lines of the outbreak, health officials use a tool called contact tracing to break the chain of transmission of the Ebola virus. That has complicated efforts to track contacts of those infected. It's a "major boots on the ground" effort that takes several hours to trace each and every contact, he said.
World Health Organization however, said in the context of an outbreak characterized by high mortality, it can be ethically appropriate to offer individual patients investigational interventions on an emergency basis outside clinical trials.
Clinicians working in the treatment centres will make decisions on which drug to use as deemed helpful for their patients, and appropriate for the setting.
"We're cautiously optimistic but there's a lot of work", said Salama. "And we've learned the hard way in the past never to underestimate Ebola".