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Value of Vaccines 2020

An overview of the Ebola virus

Professor Miles Carroll

Head of Research at the National Infections Service, PHE

The 2013-2016 Ebola virus (EBOV) epidemic caused international alarm due to its rapid and extensive spread, resulting in a significant death toll and social unrest in West Africa.

Public Health England (PHE) was involved early in the West African outbreak, establishing a laboratory to support the Médecins Sans Frontières treatment centre in Guéckédou, Guinea in March 2014.

As a member of the European Mobile Laboratory – a rapid response unit made up of a network of high containment labs – 25 PHE Porton Down scientists from multiple fields were deployed to front line diagnostic labs in Guinea, Sierra Leone and Liberia over the following 24 months.

Studying survivor immunity

The large number of cases and EU funding afforded the PHE team a unique opportunity to study the immune response of both survivors and known contacts of those infected with the virus in Guinea.

All our capabilities and resources are now being applied in the international effort to find a new vaccine against COVID-19.

This formed the most comprehensive study of EBOV survivor immunity to date, thanks to the high number of survivors involved, its three-year duration, and the analysis of both neutralising antibody and T-cell responses. The latter gives us valuable insight into how EBOV can still circulate in the bloodstream after recovery, as the virus is known to hide and then re-emerge in immune-privileged sites like the eyes and testes – the latter leading to the threat of sexual transmission.

Overcoming challenges to the study

While other studies on survivor immunology exist, only a handful look at T-cell response because of the difficulty performing assays in country and in keeping the cells viable long enough to get them out of the country; they require a -80°C setting with dry ice.

We accomplished this by employing some pragmatic approaches, such as using a WHO cooling system intended for vaccines to transport samples 600 kilometres from the remote village of Guéckédou to the capital, Conakry.

The legacy of the research

Although the full study is yet to be published, over the last three years we have been providing data to the European Medicines Agency, the US Food and Drug Administration and the WHO Vaccines Committee, to assist their regulatory review process in licensing Merck’s Ervebo vaccine and other candidates still to be licensed.

Good relationships require investment and consistent communication, and when we returned each year, we shared our latest analysis with the participating survivors.

Through the leadership network, also made up of survivors, we explained what their immune responses to the virus meant in terms of protection against re-infection and different strains of EBOV.

Looking ahead to coronavirus

Professor Miles Carroll, Head of Research at the National Infections Service, PHE, says, “The dedication of the Ebola Virus Disease (EVD) Survivors’ Association enabled us to carry out this analysis and collect data which has been critical to vaccine development.

“This undertaking required enormous teamwork from partners including the Guinean state, the UK Foreign and Commonwealth Office, and colleagues within PHE’s National Infection Service.”

“All our capabilities and resources are now being applied in the international effort to find a new vaccine against COVID-19.”

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