How can polio be prevented?

By Vaccinating. Polio is pventable disases and has been almost eradicated by active immunization program in countries like India and others By vaccinating all children with Polio Vaccine.
Vaccination. Polio vaccine as a killed virus preparaton is considered ~100% effective in preventing polio if the series is completed. Outside the US an oral vaccine - live virus(weakened) is often used and was used extensively in the US for years. There was a small risk of vaccine associated polio 8/million doses in people with weakened immunity so the US went to a killed vaccine with no such risk.