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What is it?

Polio, or poliomyelitis, is a disabling and life-threatening disease caused by the poliovirus. The virus can infect a person’s spinal cord, causing paralysis — meaning you can’t move parts of your body. Paralysis caused by poliovirus occurs when the virus replicates in and attacks the nervous system. The paralysis can be lifelong, and it can be deadly.


Fever, fatigue, headache, vomiting, stiffness in the neck, and pain in the limbs. Up to 95 percent of all persons infected with polio will have no symptoms.

How does it spread?

Through contact with the stool of an infected person (for instance, by changing diapers). Poliovirus must be swallowed to cause infection.


Four doses administered at these ages:
2 months old
4 months old
6 through 18 months old
4 through 6 years old

The first polio vaccine was available in the United States in 1955. Thanks to widespread use of polio vaccine, the United States has been polio-free since 1979. But poliovirus is still a threat in some countries. It takes only one traveler with polio to bring the disease into the United States. The best way to keep the United States polio-free is to maintain high immunity (protection) in the U.S. population against polio through vaccination. It most often sickens children younger than 5 years old.