Chromatin regulation such as dynamic changes in gene expression and chromatin structure occurs in host cells upon virus infection. Host cells activate anti-viral processes to protect themselves and viruses also invade the host cell system to create an environment useful for virus survival. Coronavirus diseas-2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV2), has been spreading all over the world since 2019, causing many kinds of severe symptoms. However, it remains unclear how SARS-CoV2 affect host cells and what chromatin regulation occurs in COVID-19. We have investigated changes in chromatin structure in the cells of COVID-19 patient with various degrees of severity, using chromatin structure analysis such as Hi-C and ChIP analysis. Severe patients tended to show severely affected chromatin patterns especially around genes in signaling pathways associated with virus infection. These results suggest that SARS-CoV2 may affect critical host cell systems and cause severe symptoms. In this symposium, we would like to discuss the relationship between COVID-19 pathogenesis and chromatin regulation.