A year in health

This year has seen the birth of the first three-person baby, a dangerous Zika epidemic and a huge injustice overturned by medical science. There were also breakthroughs in a range of deadly diseases. A year ago hardly anyone had heard of Zika virus. Now the birth of babies with underdeveloped brains - known as microcephaly - is all too familiar. The World Health Organization declared the disease, which is spread by mosquitoes, a public health emergency.