Ebola vaccine faces key test

The experimental Ebola vaccine dubbed rVSV-ZEBOV has shown promising signs that it can contain the spread of the prolific killer virus.

With a new Ebola outbreak in the Democratic Republic of Congo triggering fears of a regional threat, the vaccine is about to face its toughest test. The single-dose injection — developed by pharma company Merck and funded by the WHO and Canada’s public health agency — has been approved for use by the Kinshasa government. Roughly 7,500 doses have been sent to Equateur province in the northwest of the DRC.

It uses a modified version of the vesicular stomatitis virus (VSV), which causes illness in rodents, cattle, pigs and horses, but is not dangerous to humans.

The vaccine prompts the human body to develop antibodies against the invader so that when Ebola attacks, the antibodies are quick to identify it and fight back.

Clinical trials involving 16,000 volunteers in Africa, Europe and the United States have indicated it may be 100% effective.

The vaccine does not contain any live Ebola virus.

It can trigger side effects like cold or flu-like symptoms and swelling at the point of injection.

The “vaccine is an additional tool”, WHO spokesman Tarik Jasarevic told reporters in Geneva recently. “It does not replace all the other elements of the response.”

Because rVSV-ZEBOV remains experimental and has not been tested in the height of the epidemic, it is premature to assume that it alone can contain Ebola’s spread.

The epicentre of the outbreak is also an extremely remote, rural part of DR Congo, making access difficult. WHO has therefore conceded that “getting the vaccination teams to the affected area will be challenging”.

The vaccine also has to be stored at temperatures as low as -80C, so keeping it stable in an area with poor infrastructure creates additional complications.