Familial aggregation of COVID-19 severity suggests a genetic component to host infection response

Familial aggregation of COVID-19 cases suggest transmission occurs by contact but can also be evidence of a genetic component to the disease presentation. The goal of this work was to evaluate the disease pattern in families that many individuals have been affected by the disease. A case series analysis of six families that had many individuals affected by COVID-19 and the pattern of the severity of the disease is reported. Families were from two densely populated cities in Brazil. Participants included family members of six unrelated families, with some individuals that showed signs of COVID-19. The exposure was SARS-CoV-2 in the same household. The main outcomes and measures were disease affection and severity, including mortality. From the six families, two had mild cases only, whereas the other four families showed severe disease and death in the same sibship. The two families that had mild disease could be followed for six months and one showed reinfection after six months. This cases series suggest that disease severity aggregates in families, which suggests a genetic component for individual host response to SARS-CoV-2 infection.