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Ebola vaccination provides less protection than surviving Ebola disease
The number of Ebola-specific antibodies in the blood is as high after an Ebola vaccination as after a natural infection. However, these antibodies provide less protection against re-infection than antibodies from Ebola survivors. These new research results were recently published in the journal Viruses by the research group of Prof. César Muñoz-Fontela of the Bernhard Nocht Institute for Tropical Medicine (BNITM).
Ebola viruses belong to the group of haemorrhagic fever viruses. They can cause severe internal bleeding. Between 2013 and 2016, West Africa experienced the largest known Ebola epidemic to date which was classified by the World Health Organization (WHO) as a "Public Health Emergency of International Concern". In the following years, smaller Ebola outbreaks continued to occur in various countries, most recently in 2020 in the Democratic Republic of Congo. Since 2014, numerous vaccination studies have been conducted in Africa and scientists from around the world are looking for an effective and safe vaccines. Today, follow-up studies make it possible to compare the immune response of Ebola survivors and Ebola vaccinees. Muñoz-Fontela's research group and Prof. Marylyn Addo's team from the University Medical Center Hamburg-Eppendorf (UKE) jointly examined blood samples from Ebola survivors from Guinea and participants of an Ebola vaccination trial in Hamburg. The blood analyses were performed in the BSL4 high security laboratory at the BNITM.
The scientists looked at the immune cells and antibodies which are formed after a viral infection and are crucial for long-term immunity against the Ebola virus. Antibodies are proteins that are produced by specific cells (B-lymphocytes) and can directly bind to viruses. Some of these antibodies have the ability to neutralise viruses so that they cannot infect other human cells. In addition, during an infection other immune cells become activated and attack the viruses. The findings of the study show that Ebola survivors and vaccinees develop similarly high antibody levels. However, the neutralising antibodies are formed much better by Ebola survivors. Further, activation of immune cells is also more efficient. These results make clear that antibody titres alone do not predict actual vaccination protection. "Only if we compare the immune responses of vaccinees and Ebola survivors in detail, we wil be able to better assess the efficacy of new vaccines or other medical countermeasures" summarises César Muñoz-Fontela the findings.
About the Bernhard Nocht Institute for Tropical Medicine
The Bernhard Nocht Institute for Tropical Medicine (BNITM) is Germany’s largest institution for research, treatment and training in the field of tropical diseases and new emerging infections. The current scientific focus is on malaria, haemorrhagic fever viruses, immunology, epidemiology and clinical studies of tropical infections as well as on the mechanisms of the viral transmission by mosquitoes. For the handling of highly pathogenic viruses and infected insects, the Institute has laboratories of the highest biosafety level (BSL-4) and a BSL-3 insectary. The Institute has been appointed by the Federal Ministry of Health as the National Reference Center (NRC) for the detection of all tropical pathogens as well as by the WHO as Collaborating Center for arboviruses and haemorrhagic fever viruses. In collaboration with the Ghanaian Health Ministry and the University of Kumasi the Institute has been operating a modern research and training center in the West-African rain forest for over ten years, which is also available to external research groups.
Koch, T. et al., Ebola Virus Disease Survivors Show More Efficient Antibody Immunity than Vaccinees Despite Similar Levels of Circulating Immunoglobulins. Viruses | https://doi.org/10.3390/v12090915