The study of the safety of all medicinal products, including vaccines, begins at the stage of preclinical studies, which are conducted using experiments on laboratory animals. At this stage, their efficacy and possible adverse effects on the organs and systems of animals are assessed, and toxicity parameters are determined in order to limit risks in future clinical trials.
Since, the results of preclinical studies in animals cannot guarantee the safety and efficacy of a new medicinal product in humans owing to significant differences in enzyme systems, receptor sensitivity, etc., after preclinical studies are completed and positive results are obtained, vaccines proceed to the clinical trial stage, which comprises three phases.
Phase I. At this stage, the first experience of using the vaccine in humans is obtained. The tolerability of administering the new vaccine, possible adverse reactions, the first results of immune response formation and its duration are studied. Phase I clinical trials are conducted with the healthiest possible people in order to exclude the possible influence of other factors. A small number of volunteers take part in such trials (20-50).
Phase II. At this stage, safety is verified, and the efficacy of different vaccine doses and the duration of the immune response (antibody titer) are studied, including after repeated doses. Such trials involve hundreds of volunteers (100-300).
After Phase II is completed, the vaccine is allowed to proceed to Phase III of clinical trials, which is conducted to continue studying the efficacy of the vaccine being used and studied and to continue studying safety, since rare adverse reactions sometimes do not manifest in Phase I when applied to smaller numbers of study participants.
Phase III. Large-scale studies involving a large number of volunteers (1000-10000). During such trials, additional data are obtained: the efficacy and safety of the vaccine are confirmed, the frequency of adverse reactions and the results of vaccine use in different age groups, in persons with concomitant pathology, etc. are determined. This stage is important because rare adverse reactions sometimes do not manifest when used in a smaller number of trial participants. Such studies are the most common and are conducted simultaneously in many countries around the world.
For all vaccines proposed for registration and use in Ukraine, quality has been demonstrated and preclinical studies and Phase I and II clinical trials have been carried out in full. This allows us to state that the safety of these vaccines has been demonstrated.
When registering COVID-19 vaccines in Ukraine, the benefit/risk ratio is assessed, and only if it is positive are such vaccines recommended for registration in Ukraine.
In addition, during registration, the Applicant must submit to the authorized expert institution a Pharmacovigilance Risk Management Plan, that is, a document that analyzes the risks of possible adverse reactions and presents a plan for their minimization.
Also, the main document whose presence will necessarily be verified by the experts of the Scientific Expert Institution is the vaccine report, which includes a list of all obligations to be fulfilled by the applicant in order to complete the study of the vaccine's effectiveness.
In accordance with the commitments given, the applicant must inform the MoH, within the specified timeframes, of the assessment of the impact of available data on the benefit-risk balance, and also assess the fulfillment of certain commitments, which makes it possible to assess whether such commitments and their timeframes should be maintained or changed.
