A very small number of folks have been shown not to get infected with SARS-cov-2 (the Covid virus). They have no antibodies in their blood, and when challenged with the virus nothing happens. The current belief is that their cell surface receptor is just sufficiently different to give those folks protection against the current strains.
A larger number of folks, but still a small percentage get asymptomatic infections. Those folks have antibodies in their blood.
Having a spectrum of immune responses to viruses and communicable diseases is how species survive...
All the best,
Peter