For most children and youths, SARS-CoV-2 infection has led to a mild or asymptomatic disease, which has not necessitated admission to hospital. Although there have been several previous cross-sectional studies of the progress of Covid-19 symptoms in children and young people, there have not been any individual-level longitudinal studies that have followed the disease progression over time. In addition, no previous research has compared the longer term symptoms in this group with data from a control group that did not experience the viral infection.
A new study, published in The Lancet Regional Health – Europe, has now addressed this gap in order to understand the pattern of health and well-being in children and young people over the year following their infection with SARS-CoV-2. The study was part of the Children and young people with Long COVID (CLoCk) study, the world’s largest investigation into long COVID in children. CLoCk is a cohort study of SARS-CoV-2 PCR-positive children and young people, aged 11–17 years, matched by month of test, age, sex, and geographical area to SARS-CoV-2 test-negative individuals, using the national SARS-CoV-2 testing dataset held by United Kingdom Health Security Agency (UKHSA).
In the current research, children aged between 11 and 17 years were asked about their health six months and 12 months after taking a PCR test between September 2020 and March 2021. They were also asked to recall their symptoms at the time of taking the test. In total, data from 5,086 children were obtained, 2,909 of whom had tested positive for COVID-19, and 2,177 of whom had tested negative. The participants were asked to describe their symptoms at the time of taking the test, and at six months and 12 months afterwards.
The children and young people completed the questionnaires online, on their own, although a carer could assist younger children or those with special needs. The participants were asked what they experienced from a list of 21 symptoms, which included changes to sense of smell and taste, shortness of breath and tiredness, as well as to rate their quality of life, mental health, wellbeing and fatigue, using validated scales.
The researchers found that, at time of testing, health issues were more common in children and young people who had tested positive for the virus compared to those who had tested negative. This finding was repeated at six months and 12 months after the time of the initial PCR test. For example, among the test-positives, 10.9 percent reported fatigue at all three time points while among test-negatives only 1.2 percent reported fatigue at all three time points.
Overall, the prevalence of adverse symptoms reported at the time of a positive PCR test declined over the subsequent 12-months but, interestingly, new adverse symptoms were reported six- and 12-months post-test by both test-positives and test-negatives, particularly tiredness, shortness of breath, poor quality of life, poor well-being and fatigue. These changes would not necessarily have been identified in cross-sectional studies, revealing the value of longitudinal, individual-level follow-up studies.
“Our research goes one step further than existing studies and indicates that researchers need to track individual trajectories using repeated measurement on the same children and young people over time,” said study co-author Dr. Snehal Pinto Pereira of University College London. “Simply reporting repeated cross-sectional prevalences – or snapshots – of symptoms over time may obscure important information about long COVID in young people that has clinical relevance.”
For example, shortness of breath and tiredness, as well as some measures of poor quality of life (in particular having pain and problems doing usual activities), poor well-being and fatigue, actually increased in test-positive participants over time, when considered cross-sectionally. However, the within-individual exploration of the data demonstrates that the prevalence actually declined in those who first described these adverse symptoms either at the time of testing, or at six months, but were reported as new symptoms in some participants as the study progressed.
The fact that some of the symptoms, such as shortness of breath and tiredness also increased among participants who had tested negative for SARS-CoV-2 may indicate that these symptoms were caused by multiple factors, including the stress of living through the COVID pandemic.
The researchers say that their results highlight the value of longitudinal studies of individuals and also the importance of having appropriate control groups in order to understand the effects of SARS-CoV-2 infection. They acknowledge that some of their participants may have been infected during the study and been asymptomatic, which means this would not have been detected.
In conclusion, the researchers stress that COVID symptoms may change over time in children and young people recovering from infection, making it important to follow individual participants in order to assess the natural course of post-COVID-19 health and well-being in future.
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