I have advocated a worldwide travel shutdown exactly twice in my life: SARS, and now. SARS was a damn close call; it was stopped by proactive measures of contact tracing and quarantine (i.e. you quarantine, forcibly if need be, not only each sick person, but everyone they came into contact with); had it not been stopped, the death toll would've hit nine digits. This one looks about equally serious, and has clearly not been stopped.