University of Miami pediatrician Judith L. Schaechter gives an HPV vaccination to a 13-year-old girl last week in Miami. Joe Raedle/Getty Images hide caption

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A nurse vaccinates a child against pneumonia at a healthcare center in Managua in January. Nicaragua received pneumococcal vaccines from the GAVI Alliance. ELMER MARTINEZ/AFP/Getty Images hide caption

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Trevor Reese, 13, gets his diphtheria, tetanus and pertussis booster shot from pediatric nurse practitioner Jenny Lu in Tustin, Calif., in August. Jae C. Hong/AP hide caption

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Pharmacist Kristy Hennessee administers a vaccination against whooping cough at a Walgreen's pharmacy in Pasadena, Calif. last year. Robyn Beck/AFP/Getty Images hide caption

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An Afghan health worker administers the polio vaccine to a child during a vaccination campaign in Kabul, Afghanistan, in 2010. Majid Saeedi/Getty Images hide caption

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