There’s lots of confusion about how deadly the new coronavirus from China really is: Even health officials sometimes say “deadly” when they may mean “lethal.” Lethality is how often a disease proves fatal. That’s estimated at 2.3% in the current outbreak. Deadly is a broader concept that takes in how far and easily a virus spreads. The flu’s mortality rate is only 0.1%, yet it kills hundreds of thousands around the world each year because it infects millions. So the size of the outbreak matters as much as the lethality in terms of how deadly a disease is.
