UCalgary-led study to track how COVID-19 may be silently transmitted by children

Since the pandemic began, world-wide evidence has suggested children respond differently than adults to the coronavirus. Most children have milder symptoms and recover more rapidly. Scientists around the globe are raising questions about their role in transmitting COVID-19. Are they silent transmitters of the virus in families and communities?

“At the beginning of the pandemic, we thought children were not getting infected with the coronavirus, but now it is becoming clear that they do become infected and they definitely manifest the disease differently than adults,” explains Dr. Stephen Freedman, MD, professor of emergency medicine and paediatrics at the Cumming School of Medicine and a member of the Alberta Children’s Hospital Research Institute and O’Brien Institute for Public Health.

To understand if and how children transmit the virus, a North American team of researchers, in partnership with Alberta Precision Laboratories and the University of Alberta, is launching a fast-track surveillance study of household transmission. It is funded by the CIHR Rapid Research Funding Opportunity.

Freedman is leading the team which includes experts in infectious disease, emergency medicine, microbiology, laboratory diagnosis, virology, and public health.

As community transmission rises it becomes increasingly important for us to identify, quantify and track asymptomatic infections and to understand transmission dynamics and the risk to family members and health-care providers.

The team will offer tests to children without any evidence of COVID-19 who come to the emergency department of the Alberta Children’s Hospital and 19 other emergency departments across Canada and the United States. These sites are participating in Freedman’s CIHR-funded Paediatric Emergency Research Network (PERN)-COVID-19 study which has already recruited more than 3,500 symptomatic children who have been screened and tested for COVID-19.

Participating sites will enrol 400 asymptomatic positive children and 1,200 uninfected children who will serve as controls. All participants will receive telephone followups after 14-days of the initial emergency department visit to determine transmission patterns within the household and among other close contacts, and again at three months to assess short- and long-term outcomes. 

“We want to know if asymptomatic colonization is in fact ‘presymptomatic’ infection, how many of these children will develop symptoms, and what the transmission dynamics are in their households,” says Freedman. This information will be shared with the public and policy-makers and will guide hospital isolation practices and social distancing policies in the community, informing behaviours in schools and playgrounds. 

In addition, study participant samples that are positive for COVID-19 will undergo viral load quantification. This work is crucial to inform an understanding of transmissibility — an important, yet unknown characteristic of the virus in asymptomatic children. The findings from these laboratory tests will be integrated into a clinical followup to clarify the contribution of asymptomatic children in transmitting the virus within households, concludes Freedman.

While waiting for the results of his study, Freedman emphasizes that it is essential to adhere to the basic prevention measures researchers know are effective in limiting spread, whether a person has symptoms or not: Wear a mask. Wash hands. Keep physical distance.

"When parents make decisions about play dates or outings, they should consider the interactions in the environment and how safe it is for their kids and for others," says Freedman.   

Research team includes Dr. James Kellner, MD, professor, Department of Paediatrics and Section of Paediatric Infectious Disease at Alberta Children’s Hospital , Dr. Byron Berenger, MD, clinical assistant professor in the Department of Pathology and Laboratory Medicine and Southern Alberta lead of the COVID team at Alberta Precision Laboratories, and Dr. Anna Funk, PhD, UCalgary Eyes High Postdoctoral Fellowship.