Luz Barajas took her son Carlos Cholico to get his flu shot at Crawford Kids Clinic in Aurora, Colo., last year. Health officials say there is some evidence the flu shot is more protective than the nasal flu vaccine. Brent Lewis/The Denver Post via Getty Images hide caption

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Brent Lewis/The Denver Post via Getty Images
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New York Fertility Doctor Says He Created Baby With 3 Genetic Parents

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Swedish Scientist Starts DNA Experiments On Healthy Human Embryos

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Alicia Watkins for NPR

Breaking Taboo, Swedish Scientist Seeks To Edit DNA Of Healthy Human Embryos

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Maria Fabrizio for NPR

Researchers Question Safety, Value Of Untested Stem Cell Treatments

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Pablo Ross of the University of California, Davis, inserts human stem cells into a pig embryo as part of experiments to create chimeric embryos. Rob Stein/NPR hide caption

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Rob Stein/NPR

NIH Plans To Lift Ban On Research Funds For Part-Human, Part-Animal Embryos

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NIH Plans To End Moratorium On Funding Controversial Chimera Research

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Research Provides New Insight Into The Evolution Of Human Microbes

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A Broward County, Fla., employee takes water samples in a yard to test for mosquito larvae in June. It's part of the county's mosquito control program. Lynne Sladky/AP hide caption

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Ovarian tissue after the thaw — ready for reimplantation. Courtesy of The Infertility Center of St. Louis hide caption

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Courtesy of The Infertility Center of St. Louis

Twin Sisters Try To Get Pregnant With Ovaries They Froze In 2009

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Zika virus particles (colored purple in this scan) infecting cells. Each particle is about 40 nanometers in diameter. CDC/Smith Collection/Gado/Getty Images hide caption

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A Case Of Zika Apparently Spread From A Patient To A Family Caregiver

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The Centers for Disease Control and Prevention is updating its guidelines on preventing transmission of Zika virus via sexual activity. Stephanie Lynn/Flickr Flash/Getty Images hide caption

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