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Ebola: Experimental drugs and vaccines Ebola: The race for drugs and vaccines
(3 days later)
With more than 5,000 deaths from Ebola in West Africa, the race is on to find a cure. In September, the World Health Organization (WHO) announced that experimental treatments and vaccines for the virus should be fast-tracked. The race is on to find a cure for the disease that has killed more than 5,000 people in West Africa.
Now three research projects will take place in West Africa, testing antiviral drugs and the use of survivors' blood to treat the sick. There are no proven treatments for people with the Ebola virus or vaccines to prevent infection in the first place.
What is the current treatment for Ebola? However, progress is now being made on an unprecedented scale.
There is no licensed treatment or vaccine for the Ebola virus. Hospital treatment is based on giving patients intravenous fluids to stop dehydration and antibiotics to fight infections. Strict medical infection control and rapid burial are regarded as the best means of prevention. Trials, which would normally take years and decades, are being fast-tracked on a timescale of weeks and months.
So what are scientists doing now? Vaccines in development
They are focusing their efforts on two approaches - treatments to help people already infected with the virus and vaccines to protect people from catching it in the first place. Vaccines train the immune systems of healthy people to fight off any future infection.
There are lots of different experimental vaccines and drug treatments for Ebola under development, but they have not yet been fully tested for safety or effectiveness. Two Ebola vaccines have been rushed from promising animal studies into human trials.
The aim is get them tested and signed off for use as quickly as possible. One is produced by GlaxoSmithKline (GSK) and the National Institutes of Health in the US, and the other was designed by the Public Health Agency of Canada and is being produced by Merck.
Research projects announced GSK has inserted an Ebola gene into a weakened chimpanzee virus, which is unable to replicate in the human body.
The medical charity Medicins Sans Frontieres announced that three of its treatment centres in West Africa would each host separate research projects to try to find a cure for the Ebola virus. The first trials are due to start in December and the first results could be available in February 2015. Initial tests on 20 volunteers in the US showed it was safe and that the tiny fragment of Ebola's genetic code was enough to generate an immune response.
These three trials will research the following: Further trials are taking place in the UK, US, Switzerland and Mali to see if the immune response is strong enough to fight off an Ebola infection and how long any such protection would last.
Vaccine trials The Canadian vaccine is based on adding an Ebola gene to a virus that normally infects livestock.
Already under way are safety trials in humans of two experimental vaccines, produced by GlaxoSmithKline (GSK) and the Public Health Agency of Canada. It is being tested in the US and Switzerland, and there are plans for trials in Gabon and Kenya although no data has been published.
Normally it would take years of human trials before a completely new vaccine was approved for use but the aim is to have 20,000 doses that could be used in West Africa by early next year. Johnson and Johnson also has a vaccine in the pipeline, and the World Health Organization (WHO) is evaluating developments in Russia and Japan.
The GSK vaccine uses a chimpanzee-derived adenovirus vector with an Ebola virus gene inserted. It is being tested in Mali, the UK and the US. Vaccine challenges
Research on the Canadian vaccine is also under way in the US. It uses an attenuated or weakened vesicular stomatitis virus, a pathogen found in livestock; one of its genes has been replaced by an Ebola virus gene. The first major issue is running the clinical trials at speed, nothing like this has been done before.
Experimental treatments Ethical issues surround testing a vaccine during an outbreak, and researchers face a lack of public trust in some communities
Experimental drugs such as Zmapp have already been given to patients in the current outbreak, but they have not saved all patients. Two US aid workers and a Briton recovered after taking it, but a Liberian doctor and a Spanish priest died. The treatment is a mixture of three monoclonal antibodies that attack proteins on the surface of the virus. When the trials move to the front line of the Ebola outbreak, then it will be healthcare staff and burial workers who will be immunised.
But the medicine has only previously been tested on animals, and experts say it is still unclear whether the drug boosts chances of recovery. Stocks of the drug have also been extremely limited. Manufacturers of the drug say it will take months to increase production. There are no plans for mass vaccination of the general population before June 2015, but the WHO has not ruled it out.
What are the chances of success? There are also practical issues to address as both vaccines contains live, but weakened, virus.
Experts say pharmaceutical companies are unlikely to invest the huge resources needed to develop new drugs when these would probably be used only occasionally in relatively small numbers of people. They say investment is needed from international agencies to have any realistic chance of success in the future. It means the shots will have to be kept below minus 80C in hot countries with limited access to electricity.
The drug companies also want indemnity in case something goes wrong when they are asked to rush through a vaccine.
Promising drugs
Drug research is also taking place at pace. Instead of preventing infection like vaccines, these are designed to boost the recovery of those who have been infected.
The WHO says it is getting daily proposals for potential medicine, yet many show no activity against the virus.
Two potential drugs are being tested at Medicins Sans Frontieres facilities.
They both interfere with the way viruses replicate inside our cells:
Trials are due to start in December, with the first results expected in February 2015.
Other drugs such as ZMapp have attracted attention during the outbreak.
Two US aid workers and a Briton recovered after taking ZMapp, but a Liberian doctor and a Spanish priest died.
Like all other drugs, there is a lack of clinical evidence about whether it does work and stocks have been extremely limited so trials have been hampered.
Ethical quandary
Drugs trials are even more ethically controversial than vaccine trials in the midst of this outbreak.
Should normal randomised clinical trials take place?
It allows doctors to know for certain whether a drug is effective, but it means withholding a potentially life-saving treatment during a deadly outbreak.
One option being used is to compare survival in the same centres before and after drugs were used.
Survivor's blood
A different approach to manufacturing a drug is to harness one survivor's immune system to help another who is sick.
The body produces Ebola-fighting antibodies in response to an infection.
So the idea is to purify the blood, extract the antibodies and give those to sick patients.
Studies on the 1995 outbreak of Ebola in Democratic Republic of Congo showed seven out of eight people survived after being given the therapy.
This approach is being trialled in Guinea, led by the Antwerp Institute of Tropical Medicine.