Luke Tanner, 7, gets vaccinated for measles at a clinic near Swansea, Wales, in April. Wales is at the center of a measles outbreak that has been linked to one death.
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A cockerel walks on a bridge in a residential area of Beijing. The Chinese are beginning to destroy thousands of birds in an effort to stamp out the presumed source of H7N9 infection.
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A child is immunized against polio at the health clinic in a farming village in northern Nigeria. The procedure involves pinching two drops of the vaccine into the child's mouth. For full protection, the child needs three doses, spaced out over time.