Household SARS-CoV-2 transmission and children: a network prospective study

Soriano-Arandes, Antoni; Gatell, Anna; Serrano, Pepe; Biosca, Mireia; Campillo, Ferran; Capdevila, Ramon; Fà brega, Anna; Lobato, Zulema; López, Núria; Moreno, Ana Mª; Poblet, Miriam; Riera-Bosch, Maria Teresa; Rius, Neus; Ruiz, Montserrat; Sánchez, Almudena; Valldepérez, Cinta; Vilà , Mònica; Pineda, Valentí; Lazcano, Uxue; Díaz, Yesika; Reyes-Urueña, Juliana; Soler-Palacín, Pere

BACKGROUND: The role of children in household transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) remains uncertain. Here, we describe the epidemiological and clinical characteristics of children with COVID-19 in Catalonia (Spain) and investigate the dynamics of household transmission. METHODS: Prospective, observational, multicenter study performed during summer and school periods (1 July-31 October, 2020), in which epidemiological and clinical features, and viral transmission dynamics were analyzed in COVID-19 patients <16 years. A pediatric index case was established when a child was the first individual infected within a household. Secondary cases were defined when another household member tested positive for SARS-CoV-2 before the child. The secondary attack rate (SAR) was calculated, and logistic regression was used to assess associations between transmission risk factors and SARS-CoV-2 infections. RESULTS: The study included 1040 COVID-19 patients <16 years. Almost half (47.2%) were asymptomatic, 10.8% had comorbidities, and 2.6% required hospitalization. No deaths were reported. Viral transmission was common among household members (62.3%). More than 70% (756/1040) of pediatric cases were secondary to an adult, whereas 7.7% (80/1040) were index cases. The SAR was significantly lower in households with COVID-19 pediatric index cases during the school period relative to summer (p=0.02), and when compared to adults (p=0.006). No individual or environmental risk factors associated with the SAR were identified. CONCLUSIONS: Children are unlikely to cause household COVID-19 clusters or be major drivers of the pandemic even if attending school. Interventions aimed at children are expected to have a small impact on reducing SARS-CoV-2 transmission.