The Democratic Republic of Congo (DRC) is once again under threat of an Ebola outbreak. Can vaccines really help thwart Ebola?

Ebola Outbreak In The DRC

According to the World Health Organization (WHO), the first recorded deaths in the ongoing Ebola virus disease (EVD) outbreak in the DRC happened in January. Since then, the latest data reveals a cumulative total of 58 EVD cases which include 27 deaths from the three health zones. Of the cases, 28 have been confirmed, but 21 remain probable, and nine are suspected.

This is the ninth EVD outbreak in the DRC in the last 40 years, with the latest outbreak just last May 2017. Multiple organizations including WHO, the Ministry of Health, Ministry of Health of Guinea, Gavi, the Vaccine Alliance, UNICEF, and Médecins Sans Frontières are working together to address the outbreak.

Some of the prioritized courses of action in addressing the outbreak include community engagement, surveillance and contact tracing, infection prevention and control, case management, vaccination, and providing safe and dignified burials for the deceased.

Ebola Virus Vaccine

The rVSV-ZEBOV has proven to be an effective protection against EBV. It was found to be safe and protective against EVD after successful clinical trials which involved over 16,000 volunteers in Africa, the United States, and Europe.

The vaccine consists of vesicular stomatitis virus that has been genetically altered to also contain a Zaire Ebola protein. Vesicular stomatitis virus is an animal virus that can evoke flu-like symptoms in humans, and with the Zaire Ebola protein, it can provide an immune response to the Zaire strain of the Ebola virus.

However, despite being 100 percent effective against Ebola, the vaccine is still technically unapproved and its effects remain limited to the Zaire Ebola strain. That said, the WHO Strategic Expert Advisory Group on Immunization has previously recommended that should an outbreak of the Zaire Ebola strain occur before the vaccine has been approved, it should be immediately deployed with informed consent and in compliance with good clinical practice.

'Ring Vaccination' Strategy For The DRC Outbreak

Because of the threat of a larger-scale outbreak, vaccine administration is expected for Bikoro, Iboko, and Mbandaka, the three locations where laboratory-confirmed Ebola were recorded. However, the vaccination will not be widely distributed immediately. Instead, it will be administered using the "ring vaccination" strategy, wherein individuals with higher risks of infection because of close connections or interactions with a patient are first to be tracked down and administered with the vaccine.

This "ring" does not generally mean a geographical circle, but more of a social network of potentially at-risk individuals. This may include family members, neighbors, visitors, or anyone who may have been in contact with the sick in the past 21 days, even if they live in a fairly distant locality. Generally, such "rings" may be composed of up to 150 individuals.

This "ring vaccination" strategy is very similar to the strategy that was used to eradicate smallpox. Together with other courses of action in preventing the spread of disease, vaccination may help control the outbreak in affected communities. 

Participation in the vaccination is entirely voluntary, but children, as well as pregnant and lactating women will not be administered with the vaccine. Healthcare providers and frontline workers in affected areas will also be vaccinated.

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