You should be aware that there are different reasons why people oppose vaccination. There's the group that claims it is unhealthy, but there also are groups that oppose vaccination for religious reasons (http://en.wikipedia.org/wiki/Vaccine_controversies#Religion). You will need a religious argument to convince members of those groups (well, some members. There are indications that some of them have their children vaccinated in secret, but keep that hidden from their church members because of peer pressure)