Problem: In most subunit vaccines, the vaccine antigen is delivered via either intramuscular or subcutaneous injection*. In a subunit vaccine, there is no whole organism (attenuated or otherwise). The vaccine antigen is usually a protein or glycoprotein conjugate derived from the pathogen or toxin being vaccinated against.
These traditional protein-based subunit vaccines are better at triggering CD4+ T-cell responses than CD8+ T-cell responses.
Explain why these vaccines are better at triggering CD4+ T-cell responses than CD8+ T-cell responses.