But Polio nor smallpox was never in a pandemic stage anywhere in the world.
Is that so?
Smallpox was endemic to Europe, Asia and Arabia for centuries, a persistent menace that killed three out of ten people it infected and left the rest with pockmarked scars. But the death rate in the Old World paled in comparison to the devastation wrought on native populations in the New World when the smallpox virus arrived in the 15th century with the first European explorers.
The indigenous peoples of modern-day Mexico and the United States had zero natural immunity to smallpox and the virus cut them down by the tens of millions.
There hasn’t been a kill off in human history to match what happened in the Americas—90 to 95 percent of the indigenous population wiped out over a century. Mexico went from 11 million people pre-conquest to one million.
https://www.history.com/news/pandemics-end-plague-cholera-black-death-smallpox