Pandemics do not occur randomly. From malaria and influenza to AIDS and SARS, the lethal microbes have come, in the first instance, from animals, especially wild animals. And we increasingly know which parts of the world pose the greatest risk for future incursions.
When there is an influenza threat, drop everything and focus on risks from influenza pandemics. When SARS spreads, focus on unknown respiratory diseases. This approach helps to quell public concern, but it's a hugely inefficient way to deal with future risks.