Cellular Immune Response Induced by mRNA Vaccines Against SARS-CoV-2

The disease caused by SARS-CoV-2 is known as COVID-19, and it can range from mild symptoms to severe clinical manifestations, including respiratory failure, pneumonia, and organ failure. Since its emergence in 2019, more than 7 million deaths have been reported worldwide. Vaccines have been the most effective strategy for preventing severe illness and death in patients who acquire the infection. Vaccines induce both humoral and cell-mediated immune responses; the latter is crucial in the immune response against SARS-CoV-2, as the effector mechanisms of T-cells are less affected by the high mutation rate of the virus and prevail through memory phenotypes, ensuring long-term protection. mRNA vaccines have been primarily used worldwide to control the COVID-19 pandemic. This platform can protect against different circulating variants and is characterized by generating a robust T-cell response. This review discusses the immune response of T-cells induced by mRNA vaccines against SARS-CoV-2. It explores their effect on different population groups, including people with special clinical conditions, such as cancer and organ transplant recipients with a compromised immune system.