User blog comment:EiplecOco/Bubonic plus Pneumonic/@comment-32656-20140331152221/@comment-32656-20140405205818

Worse and more deadly are more or less the same thing - at least that is what I meant.

With influenza pandemics, however, they almost meet the right criteria for a world-killer. Just not fatal enough. Even with the regular flu virus, it still kills hundreds of thousands per year, and has large effects on society beyond that.

It is viruses.