Innovative Approach for the Clinical Development of a Chlamydia trachomatis Vaccine Through a Human-Challenge Model in Women.

Abstract

Chlamydia trachomatis remains the most common bacterial sexually transmitted infection globally. Recent Phase 1 trials of the C. trachomatis vaccine candidate CTH522 in both women and men have shown that the adjuvanted and non-adjuvanted formulations are safe and elicit systemic (IgG) and mucosal (IgA) antibodies, as well as vaccine-specific cell-mediated immunity. In advance of a standard Phase 2 randomized controlled trial to determine the vaccine's efficacy, this perspective advocates for using a carefully and ethically designed human challenge model as an innovative approach to assess a vaccine's ability to prevent infection and its impact on tubal immunopathogenesis in breakthrough infections. Such models could accelerate vaccine development by providing critical insights, making it essential for stakeholders to consider this approach and expedite the long-awaited chlamydia vaccine.