BUNIA, DR Congo: Health workers in parts of the DR Congo badly hit by a deadly Ebola outbreak launched a test vaccination program on Saturday to see if jabs designed for a different strain of the virus could prove effective in this case.


The operation, backed by the World Health Organization and the Doctors Without Borders (MSF) charity, will see 20,000 frontline health personnel given the Ervebo vaccination in the Ituri and North-Kivu provinces, in a study lasting up to a year.


The current Ebola epidemic in the Democratic Republic of Congo has killed 3,639 people out of 7,541 confirmed cases, according to the latest figures from the country's authorities. That is a fatality rate of 48.3 percent.


It is caused by the Bundibugyo strain of the virus, for which there is currently no approved vaccine or treatment.


The vaccination being rolled out as of this weekend was developed for use against the Zaire strain, and the study will determine how effective it might be against the Bundibugyo strain.


"We don't know to what degree it might be effective against the Bundibugyo strain," said Steve Ahuka, a Congolese official who is part of the health task force against the Ebola outbreak.


"It might offer a certain level of cross-protection against the Bundibugyo virus," said Nana Mimbu, an MSF research coordinator.


While WHO officials have cited "encouraging signs" that transmission may be slowing, MSF warned on Friday that there was no clear evidence that the epidemic was coming under control.


WHO experts have said that early data on the Ervebo vaccine, notably from animal trials, suggested it could offer some protection in the current outbreak.


The UN health agency said last month that 70,000 doses of the vaccine, developed by the pharmaceutical company Merck and produced in Germany, were to be sent to the DRC.


AFP journalists on Saturday saw health workers in Bunia, the main city of Ituri province, receiving vaccinations.