As of 2020, 3-4% of known COVID-19 cases worldwide resulted in patient deaths. Studies have shown that individuals infected with SARS-CoV-2, the virus responsible for COVID-19, had less T cells and fewer natural killer cells, suggesting that the immune response may play a significant role in the development, severity, and fatality of the disease. Vaccination induces an immune response in a safe way and significantly reduces your chances of developing COVID-19. Even if you've had COVID-19, vaccination will safely boost whatever immunity you have from previous infection.