The article examines the structural organization of vaccine mRNA, classification of tumor antigens, lessons from the use of vaccine mRNA in the Covid19 pandemic, the possibility of including vaccine mRNA in the genome of the vaccinated, the limitations of the immune system in terms of the existence of a continuum of protein affinity in the evolutionary hierarchy of organisms, the causes of weak immunogenicity of neoantigens. The existence of restrictions on tripeptides in the primary structure of human proteins and viruses pathogenic to it is shown. The results of the analysis of the existence of homology between several canonical and non-canonical neoantigens and various human proteins are presented. Collisions with neoantigens are considered in the aspect of the existence of an immunoepitope continuum of protein affinity, which causes the emergence of auto-tolerance of the immune system to neoantigens. Undetected or rarely occurring human and viral protein tripeptides can be used as potential biomarkers to predict the immunogenicity of neoantigens. The similarity of the structure of neoantigens to the immune epitopes of viral proteins, the infection of which induces lifelong immunity, is discussed as a possible biomarker of immunodominance and the potential to induce long-term immune memory.