The Ebola virus has created havoc in West Africa and has left global officials helpless and horrified. However, the final phase of a randomized trial in Guinea, involving an experimental Ebola vaccine, demonstrates promising initial results. According to Dr Margaret Chan, Director General of the World Health Organization (WHO), the vaccine could be a potential game-changer in the management and prevention of current and future outbreaks.
Results from the clinical trial were published in the British Medical Journal The Lancet. The next step for researchers will be to ascertain whether the vaccine could provide protection via ‘herd immunity’, and determining what percentage of people should be vaccinated in order to minimize the chances of a possible epidemic.
Significance Of The Trial
This experimental trial is an extraordinary example of how efficiently cures and vaccines can be developed if they are fast-tracked via a testing system involving drug safety and effectiveness.
Assistant Director-General Marie-Paule Kieny, who leads the Ebola Research and Development effort at WHO, said that the trial marked a revolutionary point in the history of development and research. “We now know and understand that an urgency to save lives can accelerate research and development. We will use this positive experience to develop a global ‘research and development preparedness framework’ for combating other major disease outbreaks quickly and efficiently. Using such latest medical tools, large-scale tragedies can surely be prevented”.
Testing The Experimental Vaccine
Ebola vaccine – VSV-EBOV – was developed by the Public Health Agency of Canada and NewLink Genetics USA, and is manufactured by Merck Vaccines in the US. It is described by the WHO as a ‘good’ microbe that has certain features similar to the Ebola virus but doesn’t contain the virus itself. Hence, it tricks an individual’s immune system into producing antibodies against the Ebola virus, giving them immunity against those who are actually infected.
Volunteers for the study included more than 4,000 healthcare workers, since these individuals are most likely to come into contact and be exposed to fluids of infected people. The method followed in the trial is known as ‘ring vaccination’ – people who might have come into contact are vaccinated, creating a ring that stops the virus from spreading.
Currently, half of the rings were vaccinated three weeks after someone with an Ebola infection was identified. They were compared with rings who had been vaccinated immediately. Symptoms – fever, vomiting and diarrhea – can start up to three weeks after direct contact with an infected individual.
“This strategy helped us follow the dispersed epidemic in Guinea, and provided a means to continue this trial as a public health intervention”, explained John-Arne Røttingen, Director of the Division of Infectious Disease Control at the Norwegian Institute of Public Health and Chair of the Study Steering Group.
The volunteers participated in three trial stages, firstly determining the safety of the vaccine and then assessing its efficacy in protecting people from infection. Over 2,000 volunteers were vaccinated immediately, and none of them developed the infection within a 10-day period. This is usually the time when immunity is developed.
The remaining group of about 2,000 healthcare workers was vaccinated three weeks later – only 16 of them developed Ebola. This translates into a 100 percent protection rate so far. However, the final effectiveness of the vaccine would fall somewhere between 75 and 100 percent.
New Ebola Vaccine: Hopes For The Future
Due to the strategy of isolating individuals with Ebola from those who have not been exposed, the incidence of Ebola has significantly decreased. However, pinpointing the exact rates of effectiveness of the vaccine has become a challenge. Nevertheless, researchers identified 100 infected individuals and vaccinated the people who had possibly come in contact with them.
Having established the vaccine’s safety and effectiveness, the next step would be to include teenagers and children in the trial. Side-effects such as flu-like symptoms and joint pain have been reported, but they tend to diminish after a few hours or days.