The Covid-19 vaccine is part of an attenuated virus. A person who gets a COVID-19 vaccine injection in his body will form immunity without having to be infected first.
PCR or polymerase chain reaction is a method of examining the Covid-19 virus by detecting viral DNA. But in fact, at this time PCR can not be the determinant of a person has recovered from Covid-19 or not. Self-isolation for 10-14 days and free of symptoms is the standard.