CD4 and neoplasm: In particular, replication incompetent Adenovirus vectors have been shown to achieve high levels of CD8 cytotoxic T lymphocytes besides CD4 and neutralizing antibodies, leading to the development of commercially approved Sars-Cov2 vaccines, and are currently being tested in the clinic for the development of a new generation of therapeutic vaccines based on tumor neo-antigens (27, 28).