Over the last century, widespread vaccination efforts have given patients protection against a handful of deadly infectious diseases.

Polio, rubella, diphtheria, measles, and smallpox and are among the diseases that vaccines have helped to dramatically reduce or eliminate in the US.

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From the introduction of the smallpox vaccine in the 19th century to the mass availability of flu shots today, vaccines have helped millions of people develop immunity to some of the world's deadliest illnesses.

Thanks to vaccines, many infectious diseases — like smallpox and polio — no longer exist outside of laboratories in the US. Their lasting elimination has spurred researchers to work to develop new types of immunizations that could help people avoid other life-altering diseases.

Here are six once-common diseases that you no longer have to worry about thanks to vaccines.