Clinical trials (a.k.a. clinical studies) in vaccinology are investigations with humans to assess the immunogenicity, reactogenicity i.e. the expected local or systemic symptoms of the desired immune response, safety and/or efficacy or effectiveness of vaccines.
Such investigations must be designed, conducted, and analysed based on scientific principles to get sound answers to specific questions stated in the trial plan.
Since Clinical Trials involve human subjects, highest ethical standards need to be applied.
In addition, country laws, licensing regulations and international standards, for example Declaration of Helsinki, regulate procedures and conduct of clinical trials.
Vaccine trials can be classified by development phase (phase I-III before licensure; phase IV post-licensure); by purpose; or role of the investigator.
The study protocol covers design, selection of study subjects, selection of endpoints, methods to minimize bias, conduct of the study and analysis plan, all aimed at answering the study question with best possible internal scientific validity.