COVID-19 vaccines are designed to stimulate the immune system, reducing the risk of infection, severe illness, hospitalization, and death. Different vaccines, such as mRNA, vector-based, and inactivated virus vaccines, have varying efficacy rates depending on the type, dosage, and emerging variants. Clinical trials and real-world data show that vaccines significantly lower transmission and protect individuals and communities. Booster doses enhance immunity, especially against new variants, ensuring prolonged protection.