Abstract
This review aims to evaluate the literature on the safety and efficacy of novel toxoid vaccines for the prophylaxis of Clostridium difficile infections (CDI) in healthy adults. Literature searches for clinical trials were performed through MEDLINE, ClinicalTrials.gov, and Web of Science using the keywords bacterial vaccines, Clostridium difficile, and vaccine. English-language clinical trials evaluating the efficacy and/or safety of Clostridium difficile toxoid vaccines that were completed and had results posted on ClinicalTrials.gov or in a published journal article were included. Six clinical trials were included. The vaccines were associated with mild self-reported adverse reactions, most commonly injection site reactions and flu-like symptoms, and minimal serious adverse events. Five clinical trials found marked increases in antibody production in vaccinated participants following each dose of the vaccine. Clinical trials evaluating C. difficile toxoid vaccines have shown them to be well tolerated and relatively safe. Surrogate markers of efficacy (seroconversion and geometric mean antibody levels) have shown significant immune responses to a vaccination series in healthy adults, indicating that they have the potential to be used as prophylaxis for CDI. However, more research is needed to determine the clinical benefits of the vaccines.