Exponential decay is exponential growth in reverse, so for example, if the R were 2 during the growth phase, and the R is now 0.5, you would expect it to take the same amount of time to decrease as it did to build up.

If the R were reduced to 0.99 it would take years to go away. To give you an idea, after 10 rounds of people getting infected, spreading it onward, and recovering, the number of cases would only have decayed to around 90% of its peak value (0.99 ^ 10 = 0.904)

Why would it just disappear? There are reports of secondary waves of infection and long-term health impacts for those who managed to recover.

Also public health is separate from the economy which is on the edge of another great depression with 10M unemployment claims in the US alone.

The correct model is that of bacteria in a petri dish. As long as you have a few bacterium left, they can regrow. And as long as we're getting reports of a few cases in major cities or countries, those cities or countries will lock down. So it doesn't matter how many bacteria are left as much as how long it takes to get the last remainder eliminated.

The pandemic might disappear in a few weeks. It will take far longer to fix the economic debacle.

yup- just like Trump predicted- a Miracle!