Vaccines 101: What Are Vaccinations?

Childhood vaccinations have curbed the spread of highly contagious, life-threatening diseases for centuries, yet questions about their safety and necessity persist. Here's what you need to know.

What Are Vaccinations? Are They Necessary?

What's the difference between vaccinations and immunizations?


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Although these words are often used interchangeably, they mean different things. Vaccinations describe the process of giving vaccines (in the forms of injections, oral drugs, or nasal sprays) to stimulate the production of antibodies to ward off certain diseases. Immunization is the term for making someone immune to a disease; vaccination is a form of active immunization. "When we vaccinate children, it stimulates their immune system to make antibodies that protect them against the bacteria or virus targeted by the vaccine," says Kristen Feemster, M.D., an infectious - disease specialist at The Children's Hospital of Philadelphia. You can also make someone immune by giving him pre-formed antibodies, which is called passive immunization.

Why are vaccinations necessary?

Thanks to vaccines, many infectious diseases that once routinely killed or permanently injured Americans are at all-time lows. Unfortunately, the same can't be said for other countries where diseases like measles, diphtheria, and polio continue to claim thousands of lives every year. "International travel -- both to and from the U.S. -- increases everyone's exposure risk," says Anita Chandra-Puri, M.D., a spokesperson for the American Academy of Pediatrics and a pediatrician at Northwestern Memorial Physicians Group in Chicago.

Do I have to vaccinate my child?

There's no federal mandate; however, each state has its own law that requires children to have certain vaccinations before attending public school. Children whose immune systems are compromised because of organ transplants, cancer, HIV, or other illnesses are medically exempt from certain vaccinations. Some states allow parents to opt out of vaccinations for religious or philosophical reasons. You can find your state's vaccination requirements at

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