All of it. Maybe if you diagrammed your sentence, it would help.Are you serious with this? "For example, how many ..." They/experts/doctors/immunologists/gov./gov. health care workers/health care workers, ect., ect... have all been telling us/everyone, vaccinated or not, if you get Covid a second time, you still have antibodies/built up immunities in your system to help you fight the original Covid strain, or a new mutant strain. It is still better to get vaccinated, asap, whether you test positive for it or not.
What part of this do you not understand?