VALIDATE Workshop: Vaccines for Neglected Tropical Skin Diseases – Progress and Challenges

From 6–8 May 2025, the VALIDATE Network hosted a closed workshop in Bogotá, Colombia, bringing together 28 invited delegates to tackle one of global health’s more overlooked challenges: vaccine development for neglected tropical skin diseases (NTDs). Held at the elegant Museo El Chicó, the workshop focused on leishmaniasis, Buruli ulcer, leprosy, and cutaneous tuberculosis—diseases which share common immunological features but are often sidelined in global vaccine R&D.

Day One: Introductions

Dr Maria Adelaida Gomez opened the workshop by welcoming delegates and highlighting the renewed momentum behind skin-NTD research and the potential for collective action. The morning continued with short “Turbo Talks,” during which each delegate introduced themselves, their work, and their expectations for the workshop. The quick-fire talks set a collaborative tone for the rest of the workshop..

The first morning focused on foundational overviews of the four main pathogens. Dr Olga Fernandez began with a talk on the wide clinical spectrum of cutaneous leishmaniasis and the challenges this diversity poses for vaccine development. She was followed by Prof Steve Muhi (University of Melbourne, Australia), standing in for Dr Yaw Ampem Amoako (KNUST & KCCR, Ghana), who presented an overview of Buruli ulcer disease and highlighted the shifting epidemiology and lack of vaccine tools. Dr Hua Wang (University of Strathclyde, UK) gave a historical and scientific overview of Mycobacterium leprae, while Prof Rajko Reljic (St George’s University of London, UK) offered a brief presentation on tuberculosis with a focus on its cutaneous forms. These sessions provided a shared knowledge base that would support comparative discussions later in the programme.

The afternoon moved to funders' and organisational perspectives. Dr Sundeep Vedithi (University of Cambridge, UK) discussed the development of point-of-care diagnostics and LepVax, a promising leprosy vaccine candidate. Jeanette Hayes (Wellcome Trust, UK) shared Wellcome’s current investments and future priorities in infectious disease research, with emphasis on TB and leishmaniasis. Luis Calzadilla and Chabelly Medina (British Embassy, Colombia) provided an overview of the UK’s Science and Technology portfolio in Colombia, and Dr Daniel Argaw Dagne (World Health Organisation, Switzerland) spoke on the integrated management of skin NTDs and key research gaps. The day concluded with a round-table discussion addressing the role of funders in raising disease awareness, monitoring project impact, prioritising vaccine targets, and forming effective public-private-academic partnerships.

Day Two: Pathogenesis & Vaccines in the Field

Day two focused on pathogenesis, immune mechanisms, and vaccine innovation. The morning began with Dr Adelaida Gomez (CIDEIM, Colombia), who examined how immune responses in cutaneous leishmaniasis can drive tissue damage rather than parasite clearance. Prof Rachel Simmonds (University of Surrey, UK) followed with a talk on the virulence factor mycolactone and its disruptive effects on host cellular physiology in Buruli ulcer. Dr Márcia Rodrigues Jardim (Fiocruz, Brazil) spoke about the pathogenesis of leprosy and the critical importance of early diagnosis, especially in relation to peripheral nerve damage. Prof Adrie Steyn (Africa Health Research Institute, South Africa, and University of Alabama, USA) then presented detailed insights into human TB lesions using cutting-edge spatial transcriptomics and multiplex imaging. These talks were followed by a round-table session that explored shared and divergent immunological mechanisms across the skin NTDs, the role of systems biology, and the potential of interdisciplinary collaboration to advance understanding of host-pathogen dynamics.

The afternoon turned to recent progress in vaccine research. Prof Rajko Reljic presented data from his team’s recent work showing that a composite subunit vaccine conferred full protection against Mycobacterium ulcerans in a mouse model. Dr Camila de Oliveira (Fiocruz, Brazil) discussed the use of attenuated parasites in developing a vaccine for Leishmania braziliensis, while Dr Veronica Schmitz Pereira (Fiocruz, Brazil) reviewed the progress of a leprosy vaccine currently undergoing clinical trials and the challenges of identifying reliable correlates of protection. Round-table discussion topics included the feasibility of cross-protective vaccines, the potential for mRNA technologies in NTD contexts, and the likely impact of climate change on disease spread and research priorities.

Day Three: Modelling and Social Perspectives

The final day opened with a session on laboratory and animal models. Prof Steve Muhi returned to discuss the evolution of Buruli ulcer animal models, including upcoming plans to trial vaccines in native Australian possums. Prof Manabu Ato (National Institute of Infectious Diseases, Japan) explored the limitations of current models for leprosy and the translational efforts underway in his lab. Dr Andres Felipe Vallejo Pulido (University of Southampton, UK) presented on spatial and single-cell transcriptomics as tools for decoding local immune responses and informing antigen selection and delivery system design. The accompanying round-table addressed the future of in vitro and ex vivo systems, how human trial outcomes could be better used to refine models, and whether partially protective vaccines should continue to be pursued.

The final session turned to the social aspects of skin NTD research. Prof Maria Elena Bottazzi (Baylor College of Medicine, USA) offered a framework for integrating vaccine science with economic and policy considerations. Mrs Alexandra Cossio Duque (CIDEIM, Colombia) addressed the logistical and ethical challenges of conducting clinical research in remote rural areas. Dr Maria del Mar Castro Noriega (University of Heidelberg / CIDEIM, Germany/Colombia) discussed the role of qualitative and mixed-methods research in incorporating patient perspectives into product development. Mrs Maria Isabel Echavarria (CIDEIM, Colombia) focused on implementation science and social innovation as tools to translate interventions into real-world impact.

The final round-table discussions focused on incorporating patient perspectives into policy and product development, measuring vaccine impact beyond clinical outcomes, addressing vaccine hesitancy, and ensuring equitable access in low-income settings. Delegates also considered next steps for collaboration, including developing a joint white paper, forming thematic working groups and delivering an online seminar series.

How delegates described the workshop.