“Two big unknowns stand in the way of determining how serious the plague threat in Russia is and whether travel advisories, restrictions at U.S. ports of entry or other precautions are warranted,” Axios reports.“We still don’t know which pathogen killed a Russian researcher, or how well contained it is.”“Though public health experts say there’s no cause for Americans to panic, the episode serves as a wake-up call emphasizing the nature of global biological threats and the need for pandemic preparedness.”