The U.S. measles outbreak has shone a light on the growing number of parents opting not to vaccinate their children, despite overwhelming medical reasons to do so. Amid the often-vicious debate between anti-vaxxers and their critics, it’s gone largely unnoticed that when it comes to vaccination rates, the U.S. is out of step with the rest of the world. Last week, a group of donors that included the U.S., the U.K., and the Gates Foundation met in Germany to pledge $7.5 billion to Gavi, the vaccine alliance, to pay for its operations to 2020.