Household Transmission Dynamics and Viral Load Among Asymptomatic SARS-CoV-2 Infected Children

1. Background & Rationale:

Background: Transmission from individuals with pre-symptomatic and asymptomatic (hereafter abbreviated as pre/asymptomatic) SARS-CoV-2 infections is the Achilles' heel of COVID-19 pandemic control1. While pediatric SARS-CoV-2 infection is yet to be fully characterized, and generally children are more likely to experience asymptomatic infection or mild disease compared with adults, severe outcomes are possible. Although person-to-person spread is well described in children, as schools have been closed, the transmission risk in that environment remains unknown. More importantly, the contribution of pre/asymptomatic children to overall transmission of SARS-CoV-2 is unclear with most pediatric cases linked to a symptomatic household member. According to China's National Health Commission, 130 (78%) of 166 new infections identified on April 1, 2020 were asymptomatic. In addition, data from an adult long-term care facility in Washington indicates that symptom-based screening failed to identify a significant proportion of COVID-19 cases. Furthermore, based on RT-PCR cycle threshold values, large quantities of viral RNA were detected in pre/asymptomatic residents, suggesting the potential for transmission regardless of symptoms. Asymptomatic pediatric colonization, while reported, is poorly described.

Rationale: SARS-CoV-2 shedding has been noted to occur in minimally symptomatic and asymptomatic infected persons. Children therefore, who appear to more commonly experience mild and asymptomatic infection, may represent a significant risk of household and community transmission. Recommendations for school closures are currently based on assumptions as well as evidence gathered from influenza outbreaks where these measures are known to reduce social contacts and interrupt transmission. School closures, however, disrupt the lives of students and their families and may have negative consequences on child health16. Moreover, COVID-19 transmission modelling studies predict that school closures alone prevent only 2 - 4% of COVID-19-related deaths in the general population, much less than other physical distancing interventions. It should be noted that as school closures were in place before observational studies could begin, the secondary clinical attack rate of pre/asymptomatic children is unknown. 2. Research Questions & Objectives:

The primary objective of this study is quantify the transmission risk posted by SARS-CoV-2 in pre/asymptomatic infected children in order to inform the public health response to the COVID-19 pandemic by determining the following:

If the proportion of household members who develop symptomatic illness over the subsequent 12 days is greater among households of pre/asymptomatic SARS-CoV-2 positive children relative to negative children. Mathematical models will be developed to understand the risks associated with other community transmission settings.