This chapter describes the critical concepts surrounding the immunization of healthcare personnel (HCP), including the types of vaccines, immunological principles, occupational health considerations, and preventive measures. Immunization serves as a vital safeguard, protecting healthcare workers from vaccine-preventable diseases (VPDs) such as influenza, hepatitis B, measles, mumps, rubella, and pertussis. This chapter also addresses barriers to immunization, including vaccine hesitancy, and proposes educational interventions and policy measures to promote comprehensive immunization programs in healthcare facilities.