The U.S. has wasted at least 15 million COVID-19 vaccines since March. That total, first reported by NBC News, comes from four pharmacy chains, some states, and a number of other vaccine distributors’ reports to the Centers for Disease Control and Prevention. It’s likely an undercount, however, as not all federal and state providers have submitted their reports. The reports also do not specify why doses had to be thrown out. A CDC spokesperson told NBC that the share is a fraction of the 370 million doses administered since the vaccines were first approved. “As access to Covid-19 vaccine has increased, it is important for providers to not miss any opportunity to vaccinate every eligible person who presents at vaccine clinics, even if it may increase the likelihood of leaving unused doses in a vial,” they said.