How Does Virus Spread?
The new coronavirus is a respiratory virus which spreads primarily through droplets. This can happen when an infected person coughs or sneezes, or through saliva or discharge from the nose.
The Host

Plants
Trees, shrubs, herbs, grasses, ferns, and mosses. Absorbing water and inorganic substances through its roots.

Animals
Feeds on organic matter, having sense organs and nervous system.

Human
Most complex living being with highly developed brain function.

Bacteria
Microscopic ilving organisms that can be found everywhere. Some of which can cause disease.
What happen when the found a new host?
Virus can easily enter the new host. Every virus has evolved to target particular species. Hence, it is rare for virus to be able to transmit to new species. Virus is constantly trying to infect new species but usually fail. For example, virus adapted to infect cat usually cannot infect humans.

How does virus spread from animals to humans?
A chance mutation allows the modified virus to attach and infect a new host species. When virus genes are replicated during reproduction, they can rapidly develop random mutations. Infection occurs when the modified virus successfully encounters the new host species. The virus has overcome the naturally occurring barriers to “spillover” from one species to new type of host.
