By Kemo Cham
Nearly a decade after the deadly West African Ebola Epidemic was declared over, a study on the long term immunogenicity and experiences of survivors of the viral disease has commenced in Sierra Leone.
Researchers from Sierra Leone, Japan and the United States are investigating the long-term immune system immunological memory and experiences of survivors and their close dependents by exploring how their life styles have evolved since the end of the epidemic. They will also examine the social and contextual factors influencing these changes. The researchers say the aim of the study is to understand host-pathogen immune response among Ebola virus disease survivors and close contacts, 10 years after the deadly outbreak in West Africa. This will allow them to understand whether immune cells of the survivors and close contacts retain memory and protection against the Ebola virus. Additionally, the study also seeks to understand the long-term effects of the Ebola disease infection and the challenges faced by survivors and close contacts. Ultimately, the study will raise awareness on the challenges and adaptations faced by survivors and close contacts of one of the deadliest viruses in existence, advocate for improve support for their wellbeing, and strengthen opportunities for cross-country collaboration.
Sierra Leonean biomedical scientist and researcher, Professor Alhaji Umar N’jai, is the Lead Principal Investigator for Sierra Leone in the study. He said that the initiative will also contribute to the development of therapeutics and more effective vaccines for the virus. He also said that it will provide an opportunity to understand the genetic background of asymptomatically infected individuals.
“This study will enable us to understand Ebola host-pathogen responses as it relates to long term immunogenicity and immune memory in Ebola virus disease survivors and their close contacts, who were asymptomatic,” Prof. N’jai, who works with the University of Sierra Leone, Koinadugu College and the University of Madison in the US, told ManoReporters. “The insights gained from this study especially with characterization of B and T cells of EVD survivors and close contacts as well as production of monoclonal antibodies will contribute to the development of new therapeutics and more effective vaccines,” he added.
N’jai is working on the project alongside his long time collaborators as Lead Principal Investigators for University of Tokyo and University of Wisconsin- Madison, Prof. Yoshi Kawaoka and Dr. Peter Halfmann.
Also involved in this study as Co-investigators are Prof. Foday Sahr, Executive Director of the National Public Health Agency, Sierra Leone, and Prof. Haja Isatta Wurie of the College of Medicine and Allied Health Sciences, University of Sierra Leone.
This team has previously conducted serological studies on Ebola survivors. However, this will be the first time for a long term (over 10 years) serological study to be conducted anywhere in the world, says Prof. N’jai.
“Also, the combination of long term serological, epidemiological and anthropological study to determine post- Ebola sequelae and effects on infected persons have not been done before. We are in somewhat of a new territory with opportunities to unravel new things,” said Prof. N’jai, who is also Founder and Chief Strategist of Project 1808.
The study comes eleven years after the World Health Organization (WHO) declared an end to the West African Ebola epidemic, which ravaged Sierra Leone and its Mano River Union neighbours Guinea and Liberia. It was the largest and most severe Ebola outbreak on record, surpassing all previous outbreaks since the virus was first discovered in 1976.
WHO declared the outbreak a Public Health Emergency of International Concern (PHEIC) on August 8, 2014, and by the end of the epidemic in 2016, there were 28,616 cases and 11, 325 fatalities across seven countries, according to the UN health agency. Over 90 percent of the cases and deaths occurred in Sierra Leone, Guinea and Liberia.
Between these three countries, 17,323 people survived the virus, among them 3,589 in Sierra Leone. Abdulai Dumbuya is one of them, and he is among about 70 people volunteering in this study.
“It has been a long time since we were asked about how we are faring,” Dumbuya said at an orientation ceremony for the participants held at the 34 Military Hospital in Freetown on Friday, August 22, 2025.
“Many of us have problems like vision difficulty. I can’t walk for long distance without pain. And I developed this after my encounter with Ebola,” Dumbuya, who is a bike rider, explained.
The research team is collaborating with the umbrella Sierra Leone Association of Ebola Survivors (SLAES), for which Abdulai Kargbo is the focal person. He said at the orientation ceremony that they are embracing the study with the hope that the findings will benefit Sierra Leone and the world at large.
“Many of us have been going through a lot. The feedback from this study will benefit us all,” he said.
The orientation featured two focused group discussions, in which participants recounted their experiences and current situations. They also discussed available support systems like healthcare and livelihoods.
Many survivors of EVD have complained persistent physical symptoms like joint and muscle pain, fatigue, and vision problems, alongside significant psychological distress including anxiety, depression, and post-traumatic stress, according to various reports.
Besides looking into the causes of all this, Prof. N’jai said he and his colleagues intend to bring out the positive out of Ebola by making available crucial data to inform future healthcare responses by examining the biological mechanisms underlying these long-term complications and the support needs of survivors.
“A research like this will tell us whether post-exposure the immune system still provides protection after so many years,” says Dr Mohamed Jalloh, a PhD candidate serving as a co-investigator in the study.
“For Sierra Leone, this means we are going to lead knowledge production on Ebola globally. We will also be in a position of writing a positive story out of Ebola; from one of tragedy to one of being the solution in global health,” added Prof. N’jai.
