The Democratic Republic of Congo (DRC) faces yet another outbreak of the deadly disease, Ebola. As of 27th May, the World Health Organisation (WHO) had recorded a total of 54 possible cases of Ebola, of which 25 individuals had died.
Last week, there was the first suspected case of Ebola in the major Congolese city of Mbandaka. Mbandaka’s connections to the transportation route of the Congo River, and to the cities of Brazzaville (capital of the Republic of Congo) and Bangui (capital of the Central African Republic), have increased fears of the latest outbreak spiralling out of control in a similar way to the 2014-16 West African epidemic. The two year-long epidemic claimed over 11,000 people’s lives, mostly in the countries of Sierra Leone, Liberia and Guinea.
Hope for the improved management of future outbreaks of Ebola did emerge, however, from the devastating 2014-16 epidemic. An experimental vaccine, the rVSV-ZEBOV vaccine, was trialled on nearly 6,000 people and it appeared to have a 100% success rate – not one individual treated had a recorded case of Ebola after 10 days or longer.
What is the science, then, behind this promising medical breakthrough? And what exactly is Ebola?
Firstly, Ebola is a disease which originates from five different viruses, four of which can cause serious illness in animals and humans. It is zoonotic, which means it tends to be transmitted from animals (fruit bats are believed to be the primary carrier) to humans.
While highly infectious (contact with even a tiny number of virus particles is sufficient to infect a person), Ebola is not highly contagious as it’s only transmissible from mostly bodily fluids and direct skin contact rather than airborne. Thus, infamous as New York journalist Errol Louis’s advice in 2014 (see clip below) on how to avoid contracting Ebola was, the essence of it was correct.
Symptoms of Ebola typically include, but are not limited to, headaches, fever, dehydration, diarrhoea, impaired liver and kidney function and internal bleeding. The functional cells of the liver and lining of blood vessels are targeted by the virus. Ebola’s incubation period within the body may vary from between 2 to 21 days.
The first known human outbreak of Ebola occurred in 1976 in modern-day DRC and outbreaks of the disease have been most prevalent in Central and West Africa. Reflecting the disease’s normal geographical recurrence in its name, the disease was named after the 250 kilometre-long Ebola River, which runs through northern DRC, and was close to the first identified outbreak.
At least 12,800 deaths due to the Ebola virus disease have occurred globally since 1976. The high mortality rate of contracting Ebola, which has varied by outbreak between 25%-90% of all individuals infected, makes the rVSV-ZEBOV vaccine a development of extraordinary importance.
The rVSV-ZEBOV Vaccine works by taking a less harmful virus with some similar properties to Ebola, Vesicular Stomatitis Virus (VSV), and adding to it the glycoprotein coat of the sub-species Zaire Ebola virus. Glycoproteins are proteins with carbohydrate groups attached which cover the outside of the virus. The body’s immune system fights the non-threatening virus but, most crucially, locks onto the Ebola virus’s glycoprotein coat. If the body comes into future contact with Ebola, the immune system is able to recognise and defeat the disease.
The vaccine was inadvertently formulated by researchers in the early 2000s at the Public Health Agency of Canada’s National Microbiology Lab in Winnipeg. The medical scientists had originally been investigating whether the outer glycoprotein coat of the Ebola virus caused the disease, but soon found the combination prevented both mice and macaques from contracting Ebola later.
Although patented, the Canadian researchers could not raise the funds to move experiments from animal to human trials. In a cruel irony, considering how many more lives might have been saved had human trials taken place before, the unfolding of the devastating 2014-16 West Africa outbreak helped spark interest in funding human trials of the vaccine to emerge.
The trials were 100% successful in preventing humans from being infected with Ebola disease. However, as with any experimental drug in the post-Thalidomide era, rigorous observation of possible side effects was and is required. According to CNN, in the original study in West Africa, two people had severe reactions to the vaccine, with one individual having an allergic reaction. While 2 of the total 5,837 people trialled having severe reactions may seem trivial, it nevertheless meant the vaccine required further refinement and testing.
The current outbreak of Ebola virus disease in the DRC has not yet been declared a Public Health Emergency of International Concern (PHEIC), the WHO’s effective ‘Code Red’ for outbreaks of infectious diseases and their threat to mass populations. Congo’s Health Ministry has identified the rVSV-ZEBOV vaccine as a key part of the strategy to help contain the latest disease outbreak. Already, more than 4,500 doses have been shipped to Mbandaka.
The vaccine needs to be refrigerated at between -60 and -80 celsius, which can be difficult to ensure in countries like the DRC where electricity supplies are undependable, and being in the trial stage is quite labour intensive, with the frequency of check-ups required. Despite the data compiled by the 2015 trial of the experimental vaccine, it’s still not permitted for it to be granted to children under 6 and pregnant or lactating women.
The vaccine’s affordability, once it’s officially licensed, is also uncertain. Ostensibly, the American pharmaceutical company, Merck, own the patent and have committed publicly to ‘make the vaccine available to the world’s poorest countries at the lowest possible, not-for-profit price.’
Improved sanitation and the quarantining of infected persons will clearly still remain the primary means to control Ebola disease outbreaks, for now. However, as the WHO described it in reaction to the preliminary results of the 2015 study, the rVSV-ZEBOV Vaccine is an ‘extremely promising development’ providing hope for the future.