The approval process of a vaccine in the field of Drugs Regulatory Affairs is a highly systematic and rigorous procedure designed to ensure the safety, efficacy, and quality of the product before it reaches the population. Vaccines differ from conventional drugs because they are administered to healthy individuals, often on a large scale, which makes the regulatory scrutiny more stringent. The process typically begins with the preclinical stage and progresses through multiple phases of clinical trials, regulatory review, and post-marketing surveillance. The development starts with the preclinical stage, where laboratory and animal studies are conducted to evaluate the immunogenicity and safety of the candidate vaccine. Data on toxicity, pharmacodynamics, and potential immune response are collected. Only after satisfactory preclinical results does the vaccine proceed to human testing. Before human trials, an application such as an Investigational New Drug (IND) in the United States or Clinical Trial Application (CTA) in other regions is submitted to the regulatory authority. This application must include all preclinical data, manufacturing details, and proposed clinical study designs. Approval at this stage permits the sponsor to initiate