Once an obscure and highly technical term, it first entered common parlance when, in mid-March, President Trump suggested hydroxychloroquine as a possible treatment for COVID-19. Physicians and scientists said that randomized controlled trials involving the drug would be needed before we could know whether it was an effective treatment. More recently, media coverage of a possible coronavirus vaccine has often mentioned the term, noting that vaccines must go through such trials before the Food and Drug Administration will approve them. Indeed, it has become prominent in the news since the pandemic began. Typing the term into the search engine Google...