Younger Children May be More Likely to Transmit SARS-CoV-2 Infection Compared With Older Children

As a result of low numbers of pediatric cases early in the COVID-19 pandemic, pediatric household transmission of SARS-CoV-2 remains an understudied topic. Paul, et al. (2020) sought to determine whether there are differences in the odds of household transmission by younger children compared with older children.

This population-based cohort study took place between June 1 and December 31, 2020, in Ontario, Canada. Private households in which the index case individual of laboratory-confirmed SARS-CoV-2 infection was younger than 18 years were included. Individuals were excluded if they resided in apartments missing suite information, in households with multiple index cases, or in households where the age of the index case individual was missing. Age group of pediatric index cases categorized as 0 to 3, 4 to 8, 9 to 13, and 14 to 17 years.

A total of 6,280 households had pediatric index cases, and 1,717 households (27.3%) experienced secondary transmission. The mean (SD) age of pediatric index case individuals was 10.7 (5.1) years and 2863 (45.6%) were female individuals. Children aged 0 to 3 years had the highest odds of transmitting SARS-CoV-2 to household contacts compared with children aged 14 to 17 years (odds ratio, 1.43; 95% CI, 1.17-1.75). This association was similarly observed in sensitivity analyses defining secondary cases as 2 to 14 days or 4 to 14 days after the index case and stratified analyses by presence of symptoms, association with a school/childcare outbreak, or school/childcare reopening. Children aged 4 to 8 years and 9 to 13 years also had increased odds of transmission (aged 4-8 years: odds ratio, 1.40; 95% CI, 1.18-1.67; aged 9-13 years: odds ratio, 1.13; 95% CI, 0.97-1.32).

This study suggests that younger children may be more likely to transmit SARS-CoV-2 infection compared with older children, and the highest odds of transmission was observed for children aged 0 to 3 years. Differential infectivity of pediatric age groups has implications for infection prevention within households, as well as schools/childcare, to minimize risk of household secondary transmission. Additional population-based studies are required to establish the risk of transmission by younger pediatric index cases.

Reference: Paul LA, et al. Association of Age and Pediatric Household Transmission of SARS-CoV-2 Infection. JAMA Pediatr. Published online August 16, 2021. doi:10.1001/jamapediatrics.2021.2770