There are two types of polio vaccine. The one used where polio is circulating (oral vaccine) is a live virus and provides more protection against transmission b

There are two types of polio vaccine. The one used where polio is circulating (oral vaccine) is a live virus and provides more protection against transmission but isn't super effective and (rarely) can cause paralysis. The inactivated vaccine (injection) mostly just protects against severe disease. Here's a paper that says the oral vaccine produces 70-80% protection against transmission and the inactivated vaccine produces 20-30% protection: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2486742/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2486742/