Ebola VaccineThe Democratic Republic of the Congo (DRC) is currently facing its worst outbreak of Ebola in the country’s northeastern regions, with over 2,000 declared cases, but in cooperation with the DRC’s government, the World Health Organization (WHO) has worked to provide Ebola vaccine for those who are at risk of contracting the virus.

First declared by the DRC’s government in June 2018, the Ebola outbreak has resulted in the death of over 1,000 people, and cases have also spread into neighboring Uganda. This outbreak is the second largest ever Ebola epidemic, after the outbreak that took place in West Africa from 2014-2016. There is worry that the virus could spread across the nation’s eastern borders or into major cities.

How the WHO is Combatting Ebola with Vaccines

The Ebola vaccine that the WHO uses is known as Merck’s V920, and was first employed in the early stages of an outbreak in the DRC’s Equateur province. The WHO was able to contain the virus and put an end to the epidemic in that province in under three months, although 33 people unfortunately still fell victim to the Ebola virus. When the DRC officially declared an outbreak, the Ebola vaccine, although still unlicensed, was employed on the grounds of compassionate use. The Ebola vaccine was highly effective, achieving a nearly 100 percent protection rate for more than 119,000 people living in the eastern provinces of Ituri and North Kivu.

The WHO is following a “ring vaccination” strategy, which proved successful in fighting the epidemic in Equateur. In this strategy, all those who are known contacts of people who contracted Ebola are offered the Ebola vaccine. Then, the WHO offers the vaccine to any contacts of those, as well as to anyone classified as at particularly high risk of contracting the virus, such as healthcare workers. By forming a ring of immunity around someone that is confirmed to have Ebola, they are able to reduce the chance that the virus will spread.

However, the ring vaccination strategy is quite time consuming, as it requires what is known as “contact tracing” in which every single person diagnosed with Ebola must disclose every single person that they might have been in contact with. By following this ring vaccination strategy, the WHO was able to vaccinate more than 119,000 people from August 2018 to May 2019. However, despite the vaccine’s high success rate, the number of cases continued to grow. Due to increased occurrences of violence in the country, it is more difficult for aid workers to build these vaccination rings around those who are at risk.

Modifying the Vaccination Strategy

On May 7, 2019, the WHO’s Strategic Board of Experts (SAGE) announced new recommendations that would significantly modify the vaccination strategy in order to strengthen their fight against the virus. These new recommendations focus on adjusting the dosage of the vaccine, offering an alternative vaccine for those that are at a lower risk of contracting Ebola, expanding the scope of people that are eligible for one and working to accelerate the vaccination process. In addition, SAGE recommends that the WHO provide a different vaccine to those in affected areas that are at a low risk. Johnson & Johnson have developed a MVA-BN vaccine that is currently being investigated and is at an advanced stage in moving towards deployment.

In order to expand the scope of people that can receive the vaccine, the WHO will begin to establish “pop up” vaccination sites in villages so that everyone in an area who consents to the vaccine can receive it (the WHO says that 90 percent of people consent to the Ebola vaccine). SAGE recommends that the WHO also work to vaccinate members of neighborhoods and villages where a case has been reported within the last three weeks. Vaccinating entire villages will ensure that the virus’s movement is limited, and will definitely make it much easier to contain.

Together with the DRC’s government, WHO has made great strides in fighting against the Ebola outbreak and working to contain the virus. In establishing the ring strategy that focuses on vaccinating individuals that may have been in contact with the virus, the WHO has been successfully able to build rings of immunity. The WHO has used the highly efficacious Merck’s V920 vaccine to vaccinate over 119,000 people and continues to research additional vaccines and strategies. The WHO continues to refine their approach so they can contain the Ebola epidemic as soon as possible and save as many lives as they can.

– Nicholas Bykov
Photo: Boston University