Ebola vaccine faces reality tests in Congo surge
An experimental Ebola vaccine to be deployed in an outbreak in Democratic Republic of Congo has conquered some major scientific hurdles in giving high protection, but it now faces extreme real-world tests including heat, humidity, language barriers and lack of roads.
Because it is not yet licensed, the Merck & amp Co vaccine has been offered to Congo under a “compassionate use” protocol agreed by national and international health and ethics authorities.
This means fully informed, signed consent is needed from every person who wants the shot. And in the current Ebola outbreak, that makes logistical, cultural and language barriers the ultimate challenges, global health specialists say.
The hurdles illustrate how hard it can be to move from laboratory to real life, especially in remote communities with no functioning health systems. The Congo outbreak is a chance to reality-test a vaccine against a disease epidemic that can’t be replicated in controlled environments.
“This is going to need a highly sophisticated operation in one of the most difficult places on earth,” said Peter Salama, the World Health Organization’s deputy director-general for emergency preparedness and response.
“It’s very hot and very humid, and we’re talking about hundreds of kilometers of densely forested areas.”
The shot is designed for use in a so-called “ring vaccination.” When a new Ebola case is diagnosed, all people who might have been in recent contact with them are traced and vaccinated to try and prevent the disease’s spread.
The vaccine supplies so far will be enough to vaccinate 50 rings of 150 people, according to the WHO. It said that as of May 15, 527 contacts of Ebola cases and suspected cases had been identified and were being followed up.
Health workers will need to use translators for several local languages and explain the vaccine to leaders from different communities, Salama said.
Limited communications, health facilities and electricity, as well as the need to keep the vaccine in a “cold chain” at minus 60 to minus 80 degrees Celsius will also present challenges. If any of these elements fails, the vaccine’s potential to protect 100 percent of those immunized will go unrealized.
“These are make or break issues,” said Salama, who visited Congo last weekend. “There’s a lot of complex logistics and social science here.”
Results of a trial using the ring vaccination technique with the Merck shot, which is known as VSV-EBOV, in Guinea in West Africa in 2015 showed 100 percent protection in those vaccinated immediately.
Health experts working to contain the Congo outbreak, which was first reported on May 8, say a cold chain will be in place to get the vaccines from Congo’s capital Kinshasa to the affected areas within a few days. Then the shot could be given to local frontline medical, burial and hospital workers, who volunteer for it as early as next week.
There have been 44 suspected, probable or confirmed Ebola cases in this outbreak in Congo’s Equateur province, and 23 people have died.
The WHO said last Thursday they were more concerned when a case was confirmed in Mbandaka, a city of about a million people, which is connected to Kinshasa by the Congo River.
Jeremy Farrar, a specialist in infectious diseases and director of the Wellcome Trust global health charity, said the epidemic now had “all the features of something that could turn really nasty.”
“You can’t overrespond in this scenario,” he said. “But the vaccine must be seen in the context of an overarching public health response. Critically that means early diagnosis, early isolation, safe burials and understanding the social context. The vaccine can only be a part of the solution.” Experts also caution that acting too hastily could jeopardize the potential success of a vaccine deployment.
Micaela Serafini, a medical director for the international charity Medecins Sans Frontieres, who is helping coordinate the response to the Congo outbreak, said its teams are planning for at least 45 minutes of discussion and information-sharing with each person, with a translator present, before signed consent would be obtained.
“What we need to avoid at all costs is an uncontrolled situation in the communities affected,” she said.
Even though the vaccine has still yet to get a licence, the emergency response teams say its safety and efficacy data is strong. And despite lingering suspicions in some of the more remote parts of Africa of western medicines, experts anticipate widespread public acceptance.