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Ebola: treatments and vaccines

This factsheet is also available as a pdf.

 

The first cases of the current outbreak of Ebola virus disease in West Africa were reported in March 2014. Effective treatments and vaccines have not been extensively developed due to the scale, duration, and location of previous outbreaks.

Efforts are being made by the World Health Organisation and others to fast-track and scale up research and trials on possible diagnostics, therapies and vaccines.

Allowances can be made for the advancement of therapies where it is unethical or infeasible to conduct full-scale trials, and such as is the case with treatments and vaccines for Ebola.

 

Treatments

  • Convalescent whole blood and plasma transfusions take the blood or blood plasma from an individual who has recovered from Ebola infection, and transfers it into a patient who is currently ill. The protective antibodies found in the blood of the donor may help fight the infection in the recipient. The technique has been used successfully against diseases such as Lassa fever though it is as yet unproven against Ebola, and trials are underway in Sierra Leone and Liberia, with plans for others in Guinea. There are large numbers of people who have recovered from Ebola infection and are able to donate blood, and no regulatory hurdles to clear from bodies such as the FDA or WHO. However, there are risks of infection both to and from the patient. There are also cultural sensitivities which must be understood in ensuring the understanding and acceptance of affected communities.
  • ZMapp is a combination of three monoclonal antibodies from immunised mice, which bind and neutralise the Ebola virus. Two patients treated survived although it unclear if this was due to ZMapp. Trials in macaques were successful, and a clinical trial has recently begun in Liberia and the United States.
  • Two antivirals which affect the ability of the virus to multiply have also been trialled. Favipiravir is currently undergoing trials in Guinea, while the trial of brincidofovir in Liberia was suspended at the beginning of February as the result of reduced patient numbers in the country.
  • RNA-based drugs and the repurposing of existing pharmaceuticals are also being considered.

 

Vaccines

  • Vaccines work by stimulating the body’s immune system to recognise and fight against a specific disease, priming it so that it has the tools to combat future infections.
  • Healthcare workers in affected countries including front line medical staff, lab workers and burial teams expected to be prioritised for vaccination, which should be feasible in early 2015.
  • Three candidate vaccines have been shown to be safe and protective in animal models, and are moving into clinical trials. Data on safety in humans is currently being gathered, and trials assessing efficacy are to begin soon.
  • Healthcare workers in affected countries including front line medical staff, lab workers and burial teams expected to be prioritised for vaccination, which should be feasible in early 2015.

 

cAd3-ZEBOV – GlaxoSmithKline and US National Institute of Allergy and Infectious Diseases

  • Uses an adenovirus (common cold) from chimpanzees, modified so that it cannot replicate in humans, along with the insertion of a gene for a protein on the surface of the Ebola virus.
  • 10,000 doses due to be available by start of 2015, monthly capacity expected to rise to 230,000 doses by April.
  • Phase I clinical trials showed promising results, phase II ongoing in non-affected West African countries, including Cameroon, Ghana, Mali, Nigeria and Senegal, with a phase III trial ongoing in Liberia.

 

rVSV-ZEBOV – Public Health Agency of Canada, NewLink Genetics and Merck Vaccines USA

  • Uses weakened vesicular stomatitis virus found in livestock which does not cause disease in humans, also with the insertion of a gene for an Ebola virus surface protein. An immune response may be induced which could include fever similar to that seen in Ebola patients, and so would need to be monitored.
  • 52,000 – 5.2 million doses expected in first quarter of 2015, depending on dose selected.
  • Phase III trials to test the efficacy of cAd3-ZEBOV in Guinea, following successful phase I and II trials.

 

Ad26-EBOV and MVA-EBOV – Johnson & Johnson and Bavarian Nordin

  • Uses an approach called heterologous prime-boost in which two doses are given with a different vaccine are used for each dose. Phase I trials have recently begun in the UK.

A number of other vaccines are also in development, though further behind in the developmental and regulatory process.

 

Glossary

Phase I clinical trial: designed to test the safety of the drug/vaccine in a small number of people.

Phase II clinical trial: designed to test efficacy in a larger number of people.

Phase III clinical trial: compares the drug vaccine against the current gold standard.

Phase IV clinical trials: post-licence monitoring.

 

The SMC has also produced factsheets on Ebola virus background information, as well as UK preparedness.

 

Sources / further information

World Health Organization Ebola vaccines, therapies, and diagnostics Q&A

World Health Organization Ebola Ebola vaccines

World Health Organization Ebola R&D Effort – vaccines, therapies, diagnostics

 

 

This is a factsheet issued by the Science Media Centre to provide background information on science topics relevant to breaking news stories. This is not intended as the ‘last word’ on a subject, but rather a summary of the basics and a pointer towards sources of more detailed information. These can be read as supplements to our roundups and/or briefings.

 

Updated 05/03/2015

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