Over 1,000 children from Northern Ireland, Scotland, England and Wales, known as 'COVID Warriors' have had their antibodies measured in the UK-wide trial called 'Seroprevalence of SARS-Cov-2 infection in healthy children'.
The findings have been published today (Friday 28 August) as a pre-print on the server medRxiv.
The study is led by Queen's University Belfast, in partnership with the Belfast Health and Social Care Trust Northern Ireland and Public Health England.
The aim of the study, which began in May and is ongoing, is to assess the number of children who have had COVID-19, the symptomatology of infection and if those children have antibodies that may be able to fight off the infection.
To conduct the study, the researchers are measuring children's COVID-19 antibodies via blood tests at baseline, with further tests planned at two months and six months.
The researchers have found that following the first wave of the pandemic, seven per cent of the children tested positive for antibodies, indicating previous infection with COVID-19.
Half of the children with COVID-19 reported no symptoms, and gastrointestinal (GI) symptoms (such as diarrhoea and vomiting) were also more common than cough or changes in the children's sense of smell or taste, which may have implications for the testing criteria used for children.
The findings also showed young children under 10 years of age were just as likely to have evidence of prior infection as older children, and that asymptomatic children were just as likely to develop antibodies as symptomatic children.
Dr Tom Waterfield, researcher from the Wellcome-Wolfson Institute for Experimental Medicine at Queen's University Belfast and lead on the study said:
"Following the first wave of the pandemic in the UK, we have learnt that half of children participating in this study are asymptomatic with SARS-CoV-2 infection, and those with symptoms do not typically have a cough or changes to their smell/taste, with GI upset a far more common symptom.
"This study has shown that we may want to consider refining the testing criteria for children to include GI symptoms."
Health and Social Care Research & Development Division (HSC R&D Division) of the Public Health Agency plays an ongoing role in supporting the conduct of high-quality health and social care research and has provided funding to support the delivery of this important study.
Research studies are vital at this time, and thanks to efforts such as the COVID Warriors study, we now know more about COVID-19 in terms of the exposure of children in the UK to the SARS-CoV-2 virus since the pandemic began. These significant findings can now be explored further as this research continues to monitor community transmission in children, to help tackle the spread of COVID-19."
Professor Ian Young, Chief Scientific Advisor and Director of HSC Research and Development
The study is supported by funding from HSC R&D Division, Public Health Agency, The Belfast Health and Social Care Trust and is also subsidised by a donation from the Queen's Foundation thanks to a past graduate of the University through a charitable gift in their will.
It is being delivered in partnership with The Belfast Health and Social Care Trust, Public Health England, the Ulster Independent Clinic, NHS Glasgow and Greater Clyde, Manchester University NHS Foundation Trust and Cardiff and Vale University Health Board.