The risk of severe illness and death from SARS-CoV-2, the virus that causes COVID-19, is extremely low in children and teenagers, according to a new comprehensive analysis of public health data released on 9 July by researchers in the UK.

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However, the analyses also found that COVID-19 increases the likelihood of serious illness in the most vulnerable young people, those with pre-existing medical conditions and severe disabilities, although these risks remain low overall. The preliminary findings, published in three new pre-print studies led by University College London (UCL), the University of Bristol, University of York and the University of Liverpool, will be submitted to the UK's Joint Committee on Vaccination and Immunisation (JCVI), the Department for Health and Social Care (DHSC)and the World Health Organisation (WHO), to inform vaccine and shielding policy for the under-18s.

These new studies show that the risks of severe illness or death from SARS-CoV-2 are extremely low in children and young people, said Professor Russell Viner from UCL Great Ormond Street Institute of Child Health and senior author on two of the studies. Those young people at higher risk are those who are also at higher risk from any winter virus or other illness that is, young people with multiple health conditions and complex disabilities. COVID-19 does however increase the risks for people in these groups to a higher degree than for illnesses such as influenza (seasonal flu), he said.

Our new findings are important as they will inform shielding guidance for young people as well as decisions about the vaccination of teenagers and children, not just in the UK but internationally, he added. The UCL-led study looked at England's hospital admissions data for young people between 2015 and 2021 and linked this to data on admissions to intensive care, deaths, and PCR testing. Lead author Dr Joseph Ward of UCL Great Ormond Street Institute of Child Health said: "Factors linked to a higher risk of severe COVID-19 appear to be broadly consistent for both children and adults. Our study found a higher risk of admission to intensive care among young people of black ethnicity compared to white, as well as among young people with health conditions such as diabetes, asthma and cardiovascular disease. Young people with multiple conditions had the highest risk". These conditions were also risk factors for other illnesses leading to admission to intensive care, but to a lesser degree than for COVID-19.

One preprint study, published on the medRxiv' server, found that 251 young people aged under 18 in England were admitted to intensive care with COVID-19 during the first year of the pandemic, until the end of February 2021. The researchers, seeking to determine absolute risk, said this equated to young people of that age group in England having a one in approximately 50,000 chance of being admitted to intensive care with COVID-19 during that time.

Our meta-analysis found similar risk factors to the other studies, although we also found that obesity increased the risk of severe COVID-19 illness, something we've known for some time in adults but is only now becoming evident as an important risk in children and young people too, said Dr Rachel Harwood from the University of Liverpool. Looking separately at PIMS-TS, a rare inflammatory syndrome in children caused by COVID-19, the researchers found that 309 young people were admitted to intensive care with this condition equating to an absolute risk of one in 38,911.

Dr Clare Smith of the University of Bristol noted: We found that only 40 per cent of children and young people who had a positive COVID-19 test at the time of death actually died from COVID-19, emphasising that the risks are lower than simple numbers might suggest. Children and young people with complex neurodisability were at the highest risk of death.

Senior author Professor Lorna Fraser from the University of York added: It's important to remember that the risks are very low for all children and young people. Even when we found higher risks for some groups with severe medical problems, these risks were still very small compared to risks seen in adults. A linked preprint study, published on the ResearchSquare' server and looking at data for England, concluded that 25 children and young people had died as a result of COVID-19, equating to an absolute risk of death from COVID-19 of one in 481,000, or approximately two in a million.

Dr Elizabeth Whittaker from Imperial College London said it is reassuring that the overall findings reflect the clinical experience in the hospital of very few seriously unwell children. Although this data covers up to February 2021, this hasn't changed recently with the Delta variant. We hope this data will be reassuring for children and young people and their families, she said.