This study adopts a family life course perspective to explore the health implications of intrafamilial transmission of COVID-19, asking whether the diagnosis of specific core family members (i.e., spouse, parents, children) exacerbates COVID-19 patients’ illness severity, and whether this impact varies by age. We draw on data from two cities in China, where all COVID-19 patients were immediately hospitalized upon diagnosis. Survival modeling shows that having a spouse who is also infected with COVID-19 predicts significantly extended hospital stay, an effect that is stronger for older patients than for younger ones. Additionally, having an infected parent is associated with lengthened hospital stay, whereas younger patients experience worse outcomes from parental-child tie infection. These results are congruent with the literature that expects negative consequences of family members’ illness on one’s own health. They also call for more theorizing on the evolving relationship between family connectedness and health over life-course processes.