Progress towards effective vaccines for Chlamydia trachomatis.

PURPOSE OF REVIEW: Effective vaccines to prevent sexually transmitted Chlamydia trachomatis (Ct) infection have eluded researchers for decades. However, recent studies of a promising vaccine in human trials, and emerging understanding of the complexity of the natural immune response to infection have provided hope for the eventual approval of a vaccine. This review highlights recent progress toward developing effective vaccines for Ct.

RECENT FINDINGS: In 2019, the first-in-human Ct vaccine, CTH522, Phase I/IIB trial was reported. Recent studies of this vaccine and its derivatives have further established CTH522 as the lead vaccine against sexually transmitted Ct. A variety of vaccines have entered the preclinical development pipeline, with researchers reporting efforts to target non-MOMP antigens, include novel adjuvants in vaccine formulations, and use alternative routes of administration to increase efficacy.

SUMMARY: While the approval of a vaccine for Ct is closer than ever, the need for careful consideration of future implementation is especially important for the successful clinical translation of Ct vaccines into humans.