How does vaccination prevent infection?

Anthony L. Komaroff, MD
Internal Medicine
The vaccination process mimics what would happen naturally when a potentially harmful bacterium or virus breaches the body's defenses, but with one essential difference -- there's no harmful germ involved. Instead, the vaccine contains a recognizable but defanged version of the pathogen. When you're vaccinated, your innate immune system is fooled into thinking that a pathogen has gotten in.

A signal goes to the adaptive immune system, which quickly launches an attack with T cells and B cells as if a real pathogen were invading, and also prepares for future attacks by the same pathogen by stimulating the production of long-lived memory T cells and B cells. Most vaccines don't prevent pathogens from entering your body; they just make sure your immune system blocks them quickly and keeps them from making you sick.

How does vaccination accomplish its goal? Most current vaccines work to mobilize antibodies, proteins generated by a type of B cell known as a plasma cell. Consequently, most of today's effective vaccines stimulate antibody-producing memory B cells.

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Vaccines & Immunizations

Vaccines & Immunizations

Vaccines are commonly given to children in the form of a shot to help prevent serious diseases like measles and mumps. Vaccines are developed using either dead strains of a disease, weakened strains, or strains of a different dise...

ase. As adults, we receive flu vaccines or may need a booster of childhood vaccines to retain immunity. Travelers may receive vaccines either as a condition of entry to a country, or on recommendation of health officials. Generally there is little or no reaction to a vaccine, but in some cases the vaccine may cause an allergic reaction or a temporary, mild illness. Some vaccines are not safe for pregnant women, so it’s important to check with a healthcare professional.

Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.