A Sudanese nurse prepares an inoculation against measles. In the case of the children who died or were sickened from the vaccine, untrained personnel administered it.
Ashraf Shazly/Getty Images
This year's flu vaccine protects against a few different virus strains, including the H1N1 seen here. The fuzzy outer layer is made of proteins that allow the virus to attach to human cells.
Two polio cases have been reported in Ukraine, where some parents are fearful of vaccinations. Above: A child receives the diphtheria, whooping cough and tetanus vaccine in a children's hospital in Kiev.