In the race to develop an Ebola vaccine, a small cancer therapy company, NewLink Genetics, has been in the shadows of GlaxoSmithKline (GSK), a big pharma company with lots of experience and far deeper resources. But at a high-level meeting held by the World Health Organization on 23 October, it became clear that NewLink, which is based in Ames, Iowa, by next spring may have more vaccine on hand than GSK, which is based in the United Kingdom. NewLink's projections come with a major caveat: It all depends on dose. Specifically, the NewLink vaccine is made from an Ebola gene stitched into a livestock pathogen, vesicular stomatitis virus (VSV). It's currently unknown whether the vaccine needs 1 million VSV particles per dose or 100 million. Early human studies now under way should answer this question. Charles Link Jr., the CEO of NewLink, has avoided media attention until now, but he spoke with Science at length about the prospects and the caveats.