Abstract
Vaccines protect the human body against acute infectious diseases and long-term sequelae associated with Hepatitis B, congenital rubella syndrome, and malignancies associated with viruses such as Human Papilloma Virus. Many of these vaccination strategies have been implemented and sustained through the National Immunization Programs of every country to reach practically every area, neighbourhood, and household in the population. Different types of vaccines are available depending on the pathogen, the disease to be prevented, and the targeted population. Vaccine hesitancy, defined as a delay in accepting or refusing immunizations despite the availability of vaccine services, has been reported by the WHO as one of the top ten global concerns. Vaccine hesitancy and seen outbreaks of diseases impede the immunization program. Hence, understanding the basic concepts of different vaccines is crucial to understanding their mode of action, benefits, risks, and potential real-life impact on protection. This review aims to provide healthcare professionals with background information about the main vaccine designs and concepts of protection in a simplified way to improve their knowledge and understanding to increase their confidence in the science of vaccination.

Key words: Immunization, Immunization programmes, Vaccine hesitancy, Nucleic acid vaccines