Zika had once been considered harmless, because about 80% of people who are infected show no symptoms. But alarms were sounded in 2015, when Brazilian officials suspected Zika as the cause of an outbreak of microcephaly brain malformation in babies. Public health officials rang the alarm predicting that millions of people would be infected. In … Continue reading A U.S. Zika Vaccine Trial Has a Problem: Mother Nature Removed the Threat of Infection