Ironically, the advanced state of public hygiene in most industrialized countries contributed to the century's epidemics. Infants or very young children became infected when open sewers were rampant, but their disease was so mild that many parents did not realize their children had polio. With the advent of indoor plumbing and other modern sanitary conditions, children were not exposed to the poliovirus in infancy and did not develop immunity. As a result, they were vulnerable to disease in late childhood and adulthood, when it posed a much more serious threat. Even if the poliovirus were eliminated in the body, damage to the nervous system is irreparable with current medical technology.
Vaccines can prevent polio, but only if a person has been immunized before exposure to the virus.
In 1953, Dr. Jonas Salk developed a chemically inactivated virus that immunized against the three types of poliovirus. This inert virus is given by injection and requires multiple doses. The oral vaccine against the disease is highly effective and inexpensive and usually provides lifelong immunity to the virus. It does, however, carry a very small chance of infecting the patient with the very disease it is meant to cure or of passing on the virus to those not vaccinated. Today, to help reduce the risk of vaccine associated paralytic polio, the U.S. Centers for Disease Control recommends vaccinating children with two doses of inactivated vaccine and two doses of oral vaccine.