Ebola: A Vaccine

Ebola is a genuinely scary disease. After the outbreak in west Africa earlier this year there must be very few people out there now who haven't heard of it. It is a part of the haemorrhagic fever cluster of diseases, causes multiple organ fever and for you to essentially start leaking your insides out of every orifice you have. It is spread via contact with infected bodily fluids and results in death in about a half of people in most outbreaks, although the recent one had a mortality rate of 70% of those infected. It is a viral infection named after the Ebola river in the DRC near where the first outbreak occurred in 1976.

The current, now fading, outbreak has wreaked a terrible toll. 11000 people have died; normal life in entire areas of Guinea, Sierra Leone and Liberia has been shut down. The seeds of fear and distrust have been sown in communities having a deep psychological effect that few people have even begun to try to understand yet. Now, though, for the first time, there could be hope. A vaccination has been produced by the Public Health Agency of Canada and a field trial has been completed, with promising results (published in The Lancet).

They used a strategy known as ring vaccination. This is where those in immediate contact with a symptomatic individual; friends, family, colleagues, neighbours; are vaccinated thereby forming a 'ring' of immunity around the test case. There were two groups in the study; group one was where all individuals in the ring were immediately vaccinated without delay; group two were also all vaccinated but only after a delay of 21 days. Previous, smaller trials had proved so effective that it was considered unethical to deny some people the vaccination.

In the second group, where treatment was delayed, there were 16 subsequent cases out of 3528 vaccinated. In the first group, that had immediate treatment, there was no cases at all out of 4123 people. That is a fantastic result for a vaccine that only began development a year ago; normally it would take a good decade to make that sort of progress. The trial took place in Guinea and now the powers that be are quickly trying to get through the red tape required to get the vaccine into Liberia and Sierra Leone. This might not be the end of the story, though; there are 5 species of ebola virus and we don't know how well the vaccine will work on each of them; we would also need to test more people to gain a fuller understanding of the potential side effects; and technically this isn't a licensed treatment yet, but everything is being done to smooth its path to widespread use. Plus, the vaccine has to be stored at -80 degrees Celsius, which isn't always an option in the poorly funded and equipped countries where ebola is prevalent. On the upside, GAVI, the global vaccine alliance, has pledged $390 million dollars to getting the vaccine to where it needs to be. There are also other vaccines in the pipeline which, together, may spell the end of outbreaks on the kind of devastating scale we have seen in the last year.

Electronmicrograph of an ebola virion. Image courtesy of the Centres for Disease Control