vaccination

What is the Islamic point of view regarding vaccinating children against specific diseases? Scholars of Kano in northern Nigeria issued a fatwa to the effect that it is not lawful to vaccinate their children against polio. According to them, the vaccine contains chemicals and hormones that may cause women to be infertile or impure elements that should not enter the body. In fact, the people of Kano followed the fatwa, and this resulted in the spread of polio among the children of the state. About 335 children have become paralyzed by polio. Moreover, travelers have carried the poliovirus to eight other Muslim countries. What is your point of view on this?

As-salamu `alaykum. What is the ruling on giving preventive treatment such as vaccinations? There is evidence to prove that they can be harmful to the body, but they are required in many countries.