A multifactorial theory explains fungal superinfection or coinfection in the COVID-19 era either by the occurrence of preexisting diseases, such as diabetes mellitus; use of immunosuppressive drugs, especially corticosteroids; and systemic immune alterations of COVID-19 infection itself, with reduced numbers of T lymphocytes, CD4 T, and CD8 T cells. Here, CD4 is linked to diabetes mellitus.