The largest ever study created and funded by the Coalition for Epidemic Preparedness Innovations (CEPI) to provide a more accurate assessment of the incidence of Lassa fever infections, has launched in several more countries in West Africa.
CEPI is providing US$ 10.3 million in funding to partners in Benin, Guinea, Liberia, and Sierra Leone to participate in the epidemiological research programme Enable, which will enrol up to 23,000 participants, including Nigeria, which began collecting participant data in December 2020. The in-country partners selected for the research are Fondation pour la Recherche Scientifique (FORS) in Benin, Phebe Hospital in partnership with the National Public Health Institute of Liberia (NPHIL) in Liberia, supported by University of North Carolina at Chapel Hill (UNC), Kenema Government Hospital in Sierra Leone (KGH) in cooperation with Tulane University, and Université Gamal Nasser de Conakry (UGANC) in Guinea, in partnership with Robert Koch Institut (RKI).
According to Dr Chikwe Ihekweazu, Director-General, Nigeria Centre for Disease Control (NCDC) Nigeria, “The Enable Lassa programme is building on collaboration among countries in West Africa most affected by Lassa fever to generate data and evidence that we urgently need for vaccine R&D. We are excited about the prospects of the project, not only in generating data for vaccine development, but also in strengthening our knowledge of the epidemiology of this disease and improving on the muchneeded interventions for disease control.”
First identified in 1969, Lassa fever is a potentially deadly haemorrhagic illness occurring across West Africa, with an estimated 1% of cases proving fatal. It is listed on the World Health Organization (WHO) R&D Blueprint as an emerging infectious disease in urgent need of research and development and is also recognised in CEPI’s ambitious $3.5bn plan to tackle future epidemics and pandemics caused by known and unknown threats.
However, our current knowledge on the annual Lassa case rate is hindered by a lack of formal and standard clinical diagnoses for the illness and significant variability and severity in symptoms, with the majority of patients who become infected thought to be asymptomatic and failing to seek diagnosis. Cases may also occur in remote regions where there are difficulties in accessing health care services for testing. As a result, the true case count is unknown and likely to be much higher than
current estimates of 100,000 to 300,000 cases per year.
The Enable study therefore aims to better understand the rate, location, and spread of Lassa virus across the region. Data collected in the countries will highlight any differences in the age and gender of people who become infected, while also providing a more accurate overview on the proportion of asymptomatic and symptomatic cases.
In addition, results from Enable will be crucial in supporting CEPI’s goal, as part of its five-year
lookahead strategy, of producing a licenced Lassa vaccine for routine immunisation. As a leading funder of Lassa vaccine development, CEPI has already supported the development of six Lassa vaccine candidates. Two of these vaccines, developed by partners Inovio and Themis Bioscience, entered Phase I trials in 2019, and a further vaccine candidate, developed by IAVI, started in-human testing this year.
Data provided from the Enable research programme may therefore guide the location and implementation of future late-stage efficacy trials to evaluate these or other Lassa vaccine candidates.
It could also help to define an appropriate vaccination strategy once a Lassa vaccine is approved for use, for example by helping to identify priority populations at risk.
The research will also support another goal in CEPI’s five-year plan assisting countries with
developing the infrastructure and expertise to undertake the epidemiological and clinical studies needed to advance vaccine development and enable such countries to take full ownership of their national health security.
“There have been a number of positive developments in the Lassa vaccine space over the past couple of years, with multiple candidates now moving into in-human testing” said Dr Melanie Saville, Director of Vaccine Research & Development at CEPI.
“To continue this momentum and to meet CEPI’s goal to get a licenced Lassa vaccine for routine
immunisation, we must therefore now advance our disease-assessment efforts to provide the critical data for future late-stage Lassa vaccine clinical trials. The results produced by the Enable research programme will be vital in contributing to this endeavour, while also providing novel information to help support healthcare workers and researchers in the region working on this potentially deadly
Enable research partners will collect data on potential infections either through ‘active case follow-up’, whereby a field worker carries out repeat health assessments on study participants through home visits or phone meetings to assess the health status of participants, or ‘passive case detection’, where
participants will be encouraged to report potential illness or to self-present at a health facility and the suspected or confirmed case is then recorded.
A subset of those enrolled will also take part in an additional assessment to look at the prevalence of Lassa fever antibodies biomarkers of the immune response–among participants. This will act as an indicator to better guide estimates of how many individuals in the general population are likely to have
previously been infected with the virus and are, at present, protected against (immune from) the
disease; it is generally assumed that a single infection with Lassa fever virus will produce life-long protective immunity.