Vaccines are one of the most effective tools in preventing infectious diseases and reducing the burden of illnesses globally. They work by stimulating the immune system to recognize and fight pathogens, such as viruses and bacteria, without causing the disease itself.

Through widespread vaccination campaigns, diseases like smallpox have been eradicated, and others, such as polio and measles, have been significantly reduced in prevalence. Vaccines not only protect individuals but also contribute to herd immunity, which helps protect vulnerable populations, such as infants, the elderly, and immunocompromised individuals, who may not be able to receive certain vaccines themselves.