No. Biological functions such as the growth of bacteria or spread of a disease are exponential functions. A bell curve describes a population distribution, not a growth process.
The spread of the covid-19 is showing a classic growth curve progression.
If that were true all human and animal life on the planet would have been killed by viruses (or some other organism) long ago.
You should also notice that it is a rare situation for a pond to be100% covered by lily pads in the real world.