What is the ratio of SARS-CoV-2 virus presence inside the nasopharyngeal cells correlate with the outside cells?
Please, what do you mean by "outside cells"? This is not aa common medical term.
The SARS-CoV-2 virus inside the nasopharyngeal cells (and inside an infected person's body) will be cleared by the person's immune system in the first few days (or 10 plus days) of infection. Only the viruses outside the body on the surface of epithelial cells can avoid the attack of the immune system. That is why COVID-19 PCR test is the only way to diagnose if someone is currently infected. Serological tests can detect antibodies to COVID-19 from blood samples, which is a marker of past infection. The severe case of COVID-19 is largely the result of the overreaction of the malfunctioning immunity.