In some zoonotic pathogens, efficient transmissibility among humans seems to be inherent from the start, a sort of accidental preadaptedness for spreading through the human population, despite a long history of residence within some other host. SARS-CoV had it, from the earliest days of its 2002–2003 emergence in Guangdong and Hong Kong. SARS-CoV has it, no matter where or why SARS-CoV may be hiding since then.
