There is no word in English for mass deaths caused by the introduction of new diseases for which a population has no immunity.  I coined a couple possible terms and emailed  Charles C. Mann, author of 1493.  He liked “nonagimate,” which, like “decimate,” would refer to the numbers dead, that is, nine out of ten for “nonagimate” rather than one out of  ten for “decimate.”

But we both agree that “pandemicide” is more easily understood as soon as one sees it.  So start using it and pretty soon it will be in the dictionary…..Barb