Limited role of children in transmission of SARS‐CoV‐2 virus in households—Immunological analysis of 26 familial clusters

Abstract

Background The impact of children on the transmission of severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) remains uncertain. This study provides an insight into distinct patterns of SARS‐CoV‐2 household transmission in case of pediatric and adult index cases as well as age‐dependent susceptibility to SARS‐CoV‐2 infection. Methods Immune analysis, medical interviewing, and contact tracing of 26 families with confirmed SARS‐CoV‐2 infection cases have been conducted. Blood samples were analyzed serologically with the use of a SARS‐CoV‐2‐specific IgG assay and virus neutralization test (VNT). Uni‐ and multivariable linear regression and mixed effect logistic regression models were used to describe potential risk factors for higher contagiousness and susceptibility to SARS‐CoV‐2 infection. Results SARS‐CoV‐2 infection could be confirmed in 67 of 124 family members. Fourteen children and 11 adults could be defined as index cases in their households. Forty of 82 exposed family members were defined as secondarily infected. The mean secondary attack rate in households was 0.48 and was significantly higher in households with adult than with pediatric index cases (0.85 vs 0.19; p < 0.0001). The age (grouped into child and adult) of index case, severity of disease, and occurrence of lower respiratory symptoms in index cases were significantly associated with secondary transmission rates in households. Children seem to be equally susceptible to acquire a SARS‐CoV‐2 infection as adults, but they suffer milder courses of the disease or remain asymptomatic. Conclusion SARS‐CoV‐2 transmission from infected children to other household members occurred rarely in the first wave of the pandemic, despite close physical contact and the lack of hygienic measures.

Risk Factors for Community and Intrahousehold Transmission of SARS-CoV-2: Modeling in a Nationwide French Population-Based Cohort Study, the EpiCoV Study

“…Overall, our results suggest that in a context where schools were open, adults rather than children were more likely to be infected outside the household and to introduce the virus into the household. This is in line with previous in-depth investigations of transmission chains which indicated a limited role of children in SARS-CoV-2 transmission early in the pandemic ( 27 – 30 ). However, the relative burden of children was reported to increase during the subsequent COVID-19 waves caused by highly transmissible variants of concern ( 31 ), raising questions about changes in the susceptibility and infectivity of children with the emergence of variants of concern ( 32 ).…”