In this bulletin video, we summarize the volunteering activities of a group of visualization researchers who provided support to epidemiological modeling during the COVID-19 pandemic. Epidemiological modeling during a pandemic is a complex and continuous process. The intraoperative workflow entails different visualization tasks at four different levels, i.e., disseminative, observational, analytical, and model-developmental visualization. The visualization volunteers were organized into seven teams, including a generic support team, an analytical support team, a disseminative visualization team, and four modeling support teams. During the volunteering activities, we encountered a few major challenges. We made an effort to address these challenges and gained useful experience.