Conference Abstract | Volume 8, Abstract ELIC2025477 (Oral 111) | Published: 15 Aug 2025
Benjamin Ian Curtis1,&, Seyram Kaali2, Sarah Kelly1, Peter Skidmore1, David Pulido-Gomez3, David Dosoo2, Elvis Wilson2, Elisha Adeniji2, Haixin Zhang3, Kwaku Poku Asante2, Sarah Gilbert3, Maheshi Ramasamy1
1Oxford Vaccine Group – Department of Paediatrics, University of Oxford, UK, 2Kintampo Health Research Centre, Research and Development Division, Ghana Health Service, Ghana, 3Pandemic Sciences Institute – University of Oxford, UK
&Corresponding author: Benjamin Ian Curtis, Oxford Vaccine Group, Department of Paediatrics, University of Oxford, UK. Email: benjamin.curtis@paediatrics.ox.ac.uk
Received: 11 Jun 2025, Accepted: 09 Jul 2025, Published: 15 Aug 2025
Domain: Infectious Disease Epidemiology
Keywords: Lassa Fever, ChAdOx1 LassaJ, Vaccine, Phase 1 trial, Immunogenicity, Safety, Adenoviral vector, UK, Ghana
©Benjamin Ian Curtis et al. Journal of Interventional Epidemiology and Public Health (ISSN: 2664-2824). This is an Open Access article distributed under the terms of the Creative Commons Attribution International 4.0 License (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Cite this article: Benjamin Ian Curtis et al., Vaccines against Lassa fever virus (VITAL): Phase 1 safety and immunogenicity studies of a Lassa fever vaccine, ChAdOx1 LassaJ, in healthy volunteers in the UK and Ghana. Journal of Interventional Epidemiology and Public Health. 2025;8(ConfProc):00111. https://doi.org/10.37432/JIEPH-CONFPRO5-00111
Lassa fever is a leading cause of viral haemorrhagic fever in West Africa, affecting 59 million people, with up to 500,000 infections and 5,000 deaths annually. Infection during pregnancy poses severe risks to mothers and unborn babies. Survivors may suffer hearing loss or long-term neurological sequelae. No licensed treatment or vaccine exists. ChAdOx1 LassaJ, a simian adenoviral vectored vaccine encoding the Lassa virus glycoprotein, demonstrated immunogenicity and protection from viral challenge preclinically. We will evaluate the safety and immunogenicity of 5×1010vp of ChAdOx1 LassaJ in Phase 1, healthy volunteer trials.
Subject to approvals, healthy adults (18–55 yrs) will be recruited to separate Phase 1 trials in the UK and Ghana. The UK trial will enrol an initial open-label cohort (n=6) receiving two doses of ChAdOx1 LassaJ 12 weeks apart, and a subsequent blinded second cohort (n=20) will be randomised 4:1 to receive 2 doses of ChAdOx1 LassaJ or placebo at a 12-week interval. We anticipate following a similar trial design in Ghana, but the blinded second cohort aims to compare a single dose of ChAdOx1 LassaJ to a prime boost regime, again with a placebo comparator. Safety data from both trials will be reviewed by an independent data and safety monitoring board.
Regulatory submissions are underway and both studies are projected to commence enrolment from Q3 2025. The primary objective is safety and tolerability post vaccination. Secondary objectives include vaccine induced humoral and cellular immune responses, with assays conducted at both sites. One and two dose schedule data will inform outbreak and routine immunisation policy in West Africa.
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