TraCK Transmission of COVID19 in Kids

Lead Research Organisation: Imperial College London
Department Name: Infectious Disease


COVID-19 can infect children without causing symptoms, meaning that spread of COVID-19 among children has been almost impossible to study. Other infections in the throat like scarlet fever spread rapidly between children, and spread from children to other household members. In contrast, it is thought that children are not major spreaders of COVID-19. Nonetheless, there is evidence that children are just as likely to have been infected with COVID-19 as adults in some communities.

If COVID-19 can be spread by children at a level similar to scarlet fever, we may be missing a vital link in preventing wider community spread of COVID-19. Our study will investigate how quickly and efficiently the virus might be spread by schoolchildren, and will include teachers and household contacts. We will investigate how long children can carry 'infectious' virus, and if the virus is present in saliva or the surrounding air. Conversely, if we find that children do not readily transmit the virus at all, our study will be able to provide a high level of reassurance to teachers, parents, and the public. The findings should provide much needed information for modelling and public health guidance.

Technical Summary

To develop refined models of the COVID-19 epidemic, and predict impact of different public health interventions, we need to understand far more about transmission of SARS-CoV2 between children and between children and adults. In contrast to adults, syndromic surveillance for COVID-19 in children is wholly insufficient, as disease is largely asymptomatic; sequential intensive testing of oral/nasopharyngeal samples is the only method to quantify or rule out transmission events. Outbreak investigation with multiple cases often occurs at too late a stage to infer transmission routes. Exploiting statutory notification systems as a trigger for rapid deployment, the study will explore two 'low signal' scenarios
(i) community COVID-19 activity and
(ii) single case in a school- child, teacher, other adult
Through a sequence of individual school cohort studies, in schools exposed to a low signal event, we will be uniquely placed to use intense longitudinal sampling of children and environment coupled with advanced virology, to address the following questions

1. Do symptomatic or asymptomatic children transmit the virus
(a) to each other?
(b) to adults in schools or household?
Or are adults more likely to be the source of infection in children?

2. What are the likely modes of transmission in the event of a positive case?
(a) do classrooms or washrooms/toilet become contaminated?
(b) is virus found in the air?
(c) is virus present in saliva or on hands of infected children?

3. How long do infected children carry viable infectious virus and when do secondary cases arise if at all?


10 25 50
Description Collaboration with Public Health England beyond HPRU 
Organisation Public Health England
Country United Kingdom 
Sector Public 
PI Contribution Proposing the research; providing research questions; capacity to undertake the experimental work and obtain ethical approval for a clinical study
Collaborator Contribution ability to conduct the clinical study at local sites and coordinate based on notification data
Impact Ethical approval submission
Start Year 2017