Long COVID in children and adolescents remains poorly understood due to a lack of well-controlled studies with long-term follow-up. In particular, the impact of the family context on persistent symptoms following SARS-CoV-2 infection remains unknown. We examined long COVID symptoms in a cohort of infected children, adolescents, and adults and their exposed but non-infected household members approximately 1 year after infection and investigated clustering of persistent symptoms within households. 1267 members of 341 households (404 children aged <14 years, 140 adolescents aged 14-18 years and 723 adults) were categorized as having had either a SARS-CoV-2 infection or household exposure to SARS-CoV-2 without infection, based on three serological assays and history of laboratory-confirmed infection. Participants completed questionnaires assessing the presence of long COVID symptoms 11-12 months after infection in the household using online questionnaires. The prevalence of moderate or severe persistent symptoms was statistically significantly higher in infected than in exposed women (36.4% 95% CI: 30.7–42.4% vs 14.2% 95% CI: 8.7–21.5%), infected men (22.9% 95% CI: 17.9–28.5% vs 10.3% 95% CI: 5.8–16.9%) and infected adolescent girls (32.1% 95% CI: 17.2–50.5% vs 8.9% 95%CI: 3.1–19.8%). However, moderate or severe persistent symptoms were not statistically more common in infected adolescent boys aged 14–18 (9.7% 95% CI: 2.8–23.6% or in infected children <14 years (girls: 4.3% 95% CI: 1.2–11.0%; boys: 3.7% 95% CI: 1.1–9.6%) than in their exposed counterparts (adolescent boys: 0.0% 95% CI: 0.0–6.7%; girls < 14 years: 2.3% 95% CI: 0·7–6·1%; boys < 14 years: 0.0% 95% CI: 0.0–2.0%). The number of persistent symptoms reported by individuals was associated with the number of persistent symptoms reported by their household members (IRR=1·11, p=·005, 95% CI 1.03–1.20). In this controlled, multi-centre study, infected men, women and adolescent girls were at increased risk of negative outcomes 11-12 months after SARS-CoV-2 infection. Amongst non-infected adults, prevalence of negative outcomes was also high. Prolonged symptoms tended to cluster within families, suggesting family-level interventions for long COVID could prove useful. Ministry of Science, Research and the Arts, Baden-Württemberg, Germany.