Recent scientific studies are prompting a reevaluation of the immune effects of SARS-CoV-2, highlighting its potential long-term impact on the human immune system. A new study published in Nature suggests that infections such as influenza and COVID-19 can reactivate dormant cancer cells, increasing the risk of cancer recurrence and metastasis. This finding has led researchers to explore strategies targeting immune surveillance, including cancer vaccines, which may help prevent the reactivation of these latent cells, assuming memory T-cells remain effective. Additionally, discussions have emerged around the unique immune effects of mRNA-based COVID-19 vaccines and their possible role in adverse events, including concerns related to tumor suppressor proteins. The evolving understanding of SARS-CoV-2’s influence challenges previous notions like the “immunity debt” theory and underscores a subtle but profound shift in immune system dynamics post-infection.