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First findings from world’s largest study on long COVID in children and young people

Published: 02 September 2021

Up to one in seven children and young people who had COVID-19 may have symptoms linked to the virus 15 weeks later, suggest preliminary findings from the world’s largest study on long COVID in children and young people.

For the study, published on the preprint site Research Square and funded by the NIHR and UK Research and Innovation (UKRI), researchers surveyed 3,065 11- to 17-year-olds in England who tested positive for SARS-CoV-2 in a PCR test between January and March. They were paired with a matched control group of 3,739 11- to 17-year-olds who tested negative over the same period.

The researchers found that, when surveyed at an average of 15 weeks after their test, 14% (one in seven) more young people in the test positive group had three or more symptoms of ill health, including unusual tiredness and headaches, than those in the test negative group, while 7% (one in 14) more had five or more symptoms.

Lead author Professor Sir Terence Stephenson, from UCL Great Ormond Street Institute of Child Health, said: “There is consistent evidence that some teenagers will have persisting symptoms after testing positive for SARS-CoV-2. Our study supports this evidence, with headaches and unusual tiredness the most common complaints.

Professor Stephenson added: “The difference between the positive and negative groups is greater if we look at multiple symptoms, with those who had a positive test twice as likely to report three or more symptoms 15 weeks later.” This suggests that a number of symptoms should be considered when clinicians seek to define long COVID in children.

The landmark study is the largest study to date of children and young people in the world: it relied on PCR lab proven SARS-CoV-2 status; it enrolled a COVID-negative comparison control group; and it recruited nationally.

High numbers of young people who tested negative for SARS-CoV-2 reported symptoms at 15 weeks. The researchers identified three factors that may explain this. One is that symptoms such as unusual tiredness are common in this age group generally. The second is that the timing of the survey, between March and May, coincided with the return of school following lockdown and a likely increase in infections. The third factor is that only 13% of those young people sent a survey responded – it is possible that these respondents were more likely to have poor health than those who did not respond.

Co-author Professor Roz Shafran, from UCL Great Ormond Street Institute of Child Health, said: “Our study also shows the importance of having a comparison group so that long-lasting COVID-19 symptoms are not confused with non-COVID-related ill health. Without a control group of young people, our findings would be uninterpretable.”

Final author Dr Shamez Ladhani, from Public Health England, said: “In addition to having a control group, one of the major strengths of this study is the follow-up of the children for up to two years, which will give us insight into any long-lasting effects of COVID-19 in teenagers.”
The researchers found that there was no difference in mental health and wellbeing scores between children who tested positive compared to those who tested negative, but a high proportion in both groups reported being a bit or very worried, sad or unhappy (41% of people who tested positive versus 39% of those who tested negative).

The research team sent questionnaires to about 220,000 young people in England and received 17,000 responses. These early results drew on the responses of nearly 7,000 of those who were tested between January and March, excluding those who were tested earlier (September to December) and therefore at greater risk of recall bias.

For later studies, the researchers will analyse survey results at six months, a year and two years from the time of the PCR test.

The Children and young people with Long COVID (CLoCk) study is led by UCL and Public Health England and involves collaboration with researchers at the universities of Edinburgh, Bristol, Oxford, Cambridge, Liverpool, Leicester, Manchester as well as King’s College London, Imperial College London, Public Health England, Great Ormond Street Hospital and University College London Hospitals (UCLH).

Professor Lucy Chappell, Chief Executive of the NIHR, said: “Parents and young people are understandably concerned about the risk of long-term symptoms following SARS-CoV-2 infection.

“This large study, part of NIHR’s £50 million investment into long COVID research, helps to quantify that risk and indicates that multiple ongoing symptoms may be a useful measure for long COVID.”

Health Minister, Lord Bethell said: “Most people who catch COVID-19 make a full and quick recovery, but we know some continue to suffer from symptoms for months after being infected. That’s why we are backing vital research like this to help build our understanding of long COVID so we can protect adults and children from its effects.

“To support people with long COVID we have already invested £50 million in research to ensure the right help and treatment is available and opened over 80 assessment services across England, including specialist services for children and young people backed by £100 million in additional funding.

“We want the UK to be a world leader in tackling long COVID and we will continue to support those suffering the long-term effects of the virus.”

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