So we could be a few mutations away from a virus that will invade the vaccinated. The more variants we get the better the chances of what?

Not being able to keep up with vaccines that WORK.

Worst case?

How about a virus that NO VACCINE will stop? How about a virus that is unaffected by any vaccine?

The unvaxxed is the lab in which the variants get a chance to increase multiply spread mutate.

They ARE the test tubes. They are the specimens looked at under the microscope to see what if any uncontrollable variations may have adapted mutated varieated.

A moving feast.