The pandemic that really threatens mankind wont be a virus, it will be a super resistant basteria. Ask anyone who works int he medical field, particularly lab techs and microbiologists and they will spin some serious nightmare tales of simple bacteria that 20 years ago could be killed by penicillin and now are resistant to the most advanced and lethal antibiotics.
Its due primarily to people taking antibiotics when they shouldn't. Flu for example is a virus but people seem to always want to take antibiotics for it. That and never completing the course of treatment. If the prescription says take it for 3 weeks, but you only take it for 2 weeks becasue your symptons go away, all you accomplished was give the surviving bacteria a bit of a resistant to the medicine you used.