Clustered coronavirus pneumonia is a clustered case, which refers to a clustered illness caused by two or more cases found within two weeks or less in a small area such as a family, workplace, or community, and the number of cases is two or more because of close contact, mutual transmission, or exposure of these cases to the same source of infection. It is characterized by aggregation, in addition, the transmission between patients may originate from the same source of infection, called aggregated cases, and the scope is relatively small. Therefore, the incidence of novel coronavirus pneumonia is characterized by aggregation of more than 70%-80% of cases, especially family aggregation of cases is the most common. Source: Dr. Yurai