9. Rotavirus
Now, two vaccines are available to protect children from rotavirus, which is the leading cause of severe diarrheal illness among babies and young children. The virus can spread quite rapidly, through what many researchers call the fecal-oral route (meaning that small particles of feces end up being consumed). Even if children in the developed world rarely die from rotavirus infection, the disease is a killer in the developing world, where rehydration treatments are not so common.
The World Health Organization estimates that worldwide, 453,000 children younger than five years old died from rotavirus infection in 2008 alone. But countries that have introduced the vaccine have reported sharp declines in rotavirus hospitalizations and deaths.
