Poliovirus can infect the nervous system and cause paralysis, including fatal paralysis of the muscles that control breathing. Polio is spread through stool or respiratory secretions from an infected person. Polio used to be common in the U.S, affecting thousands of people each year before a vaccine was introduced in 1955.
There are two types of polio vaccine. Since 2000 only injectable Inactivated Polio Vaccine (IPV) has been used in the U.S. Children get doses of IPV at 2 months, 4 months, 6-18 months, and booster dose at 4-6 years of age, usually at the same time as other kindergarten vaccines. Oral polio vaccine is given in many other countries as part of the humanitarian effort to end polio worldwide.