Children are one of God's best gifts to people, as watching their children grow is one of the best pleasures people enjoy during their life course. For this reason, parents must take good care of their children during their early years, as they are vulnerable to many diseases due to their weak immunity. There are many diseases, infecting children, that may lead to death such as the polio disease. Scientists found a solution to this problem, by injecting a tiny sample of the virus into the child's blood, in order to stimulate the immune system to fight the disease if the child catches it…
