"When Spanish Flu killed millions after the end of the first world war, it was helped to spread by troop movements (returning home) but it spread much more slowly than the current one. Even so, it killed millions."
The main reason it spread so far and killed so many was that scientists at the time were unaware or virus' and were assuming it was a bacterial problem. This would not happen today, unless of course, a new type of "bug" other than bacterial or a virus existed.
Dr. Stan MD