Viruses are just like computer viruses. A virus is just a short code (a chemical code/DNA/RNA) which is powerless till it finds a host. Once it gets entry into host it can multiply and cause damage to the host, just like it does to computers. Human body, the supreme machine has its own antivirus program (immunity) that keeps on auto-updating definitions.
It can take care of this Corona Virus too in 98% cases.
Although aged and immunocompromised people are vulnerable.