You lack reading comprehension skills. It is not about semantics. Polio vaccine has been proven its effectiveness for 50 years. Anywhere in the world where there are vaccination programmes the disease disappears. This has been shown in university studies, by various govenment health ministries and departments, (ie. Australia, Canada, UK, USA, Japan, Norway, Denmark, France, Spain and many others) and as well as by international organizations like WHO and varoius NGOs.