Severe coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS CoV-2) is characterized by pneumonia, lymphopenia, exhausted T-cell response, and a cytokine storm with high levels of interleukin (IL)-6, tumor necrosis factor (TNF)-α, monocyte chemoattractant protein (MCP)-1, macrophage inflammatory protein (MIP)-1α, and so on. Here, TNF is linked to lymphopenia.