Kristy- all these infectious diseases were in a steady decline for decades (in Australia since records were kept) long before vaccinations were introduced. Some people suggest that they would have been totally eradicated by now except that vaccines keep the virus alive- that they wouldn't be in existence if they let nature take its course. Official statistics are freely avaliable that show that vaccinated chn still get diseases and research shows that vacs don't reduce the severity of them either.