CD8A and hepatitis B virus infection: Indeed, BCG is a cellular, live attenuated vaccine, meaning that non virulent mycobacterias multiply in the host receiving the vaccine, which induces mainly a T cell response (CD4+ Th1 and CD8+), whereas the vaccines against hepatitis B, diphtheria and tetanus are acellular vaccines eliciting mainly a B cell production of IgG antibodies with the help of T cells.