Ebola outbreak in DRC sets up another test for experimental treatments

In the world of Ebola outbreaks, lucky breaks are few and far between. But it appears the Democratic Republic of the Congo may have caught a small one in its latest go-round with the dangerous disease.

And it might also give the world another shot at testing an experimental Ebola vaccine.

Officials in the DRC said Thursday that testing has shown that the virus causing disease in North Kivu province in the northeast of the country is Ebola Zaire. That is the virus targeted by Merck’s experimental vaccine, which was tested during the West African outbreak in 2014 and 2015, and used in eastern DRC in an outbreak earlier this year.

There had been concerns that, given the location of the outbreak, another species of Ebola might have been causing the illnesses. That would have meant few possibilities for experimental drugs and potentially no vaccines options.

Despite the potential of a vaccine to help in this outbreak, delivering it could prove challenging, warned Dr. Peter Salama, the head of the World Health’s Organization’s emergency response program.

Battling factions operate in the area, and there are roughly 1 million displaced people the province. The danger inherent in operating in this part of DRC means a modified approach to the vaccination rollout may be needed, Salama said.

In the outbreak earlier this year in DRC, health officials used a ring vaccination program, in which they tracked down the contacts of cases and the contacts of those contacts, and offered them all vaccine in a bid to halt spread. That approach might not be viable in North Kivu.

“The ring vaccination strategy is highly dependent on access, and really strong access to the population that’s being targeted,” Salama told STAT. “The ring vaccination is really the big question mark [here].”

Salama said consideration is being given to an “out-in strategy,” which would create a ring around an area where there had been cases, rather than trying to find and vaccinate specific individuals. The idea would be to start “with a protective buffer around a whole geographical zone,” and then moving inward, offering vaccine to everyone in the area.

A lot will depend on how freely the vaccine teams can travel. And that will be determined in negotiations with the United Nations peacekeeping operation in the region.

“We’re discussing with the U.N. what the security ceiling will be for the number of staff that they’ll allow us to deploy,” Salama said. “And also, what sort of armed vehicles, armed escorts, or otherwise that we’ll need to use. And that’s going to make it much more difficult.”

If officials are able to deliver the vaccine, there is reason to hope that people in the area will be willing to use it. During the earlier outbreak, in Bikoro, nearly 3,500 people were vaccinated and vaccine acceptance was extraordinarily high. Over 98 percent of people offered the vaccine agreed to be vaccinated.

The fact that the Ebola Zaire virus is the cause of the outbreak also opens up the most options for experimental drugs to treat patients. In addition to the Merck vaccines, supplies of five potential therapeutics are already in the country, having been sent during the Bikoro outbreak.

None of the drugs was used during the previous outbreak. By the time DRC’s scientific and ethical committees reviewed the available scientific data and authorized the drugs for compassionate use, there were no more Ebola patients in care.

But that review process should speed usage of the drugs this time, Salama said. He said the drugs will be used on a compassionate basis.

Three of the experimental therapeutics are monoclonal antibodies — immune system combatants that can recognize and combat Ebola. They are: ZMapp, produced by Mapp Biopharmaceutical; REGN3470-3471-3479, made by Regeneron; and an early stage therapeutic called mAb 114, which is a joint project of the DRC’s National Institute of Biomedical Research and the National Institute of Allergy and Infectious Diseases.

There is also an antiviral drug, Remdesivir, which is being developed by Gilead, and a small supply of a Japanese influenza antiviral call favipiravir.

 — This article was updated to note a fifth experimental Ebola drug is in the Democratic Republic of the Congo.