Although COVID-19 symptoms are similar in children and adults, most children with SARS-CoV-2 infection have mild, or even no, symptoms. Children can also experience different Long COVID symptoms than adults and they may have unique healthcare needs. For this reason, the clinical definition for Long COVID in adults, which was released in October 2021, may not be useful in children and teenagers.
But why do we need a definition at all? The WHO underlined that the new global definition will encourage physicians, patients, caregivers, teachers and others to talk about Long COVID. It will also help researchers to study Long COVID more reliably because we still don´t know much about this condition, for example about symptoms, risk factors and disease course in children.
Fatigue, changes in smelling and anxiety are more common in children with Long COVID than healthy children.
The WHO definition for Long COVID in children
The definition states that post-COVID-19 condition, or Long COVID, in children and teenagers “occurs in individuals with a history of confirmed or probable SARS-CoV-2 infection when experiencing symptoms lasting at least two months which initially occurred within three months of acute COVID-19.” This definition applies to children of all ages.
In addition to fatigue, altered smell or loss of smell (anosmia) and anxiety, further 21 potential Long COVID symptoms are listed, including headache, loss of appetite, cognitive difficulties and insomnia. The WHO noted that these symptoms can change daily functioning, for example, eating habits, physical activity, behavior, educational performance and social interaction (with friends, peers and family). Symptoms may appear after recovery from COVID-19 or remain after the initial illness.
This definition may change as our knowledge steadily expands.
Definition emerged from scientific data
The basis of the new Long COVID definition in children were the results from a systematic review and meta-analysis completed by the UCL Great Ormond Street Institute of Child Health from London. This large analysis included 60 previously published studies with a total of 328,875 participants. In this study, children and teenagers who had SARS-CoV-2 infection were compared to those without a history of COVID-19 or who had tested negative for SARS-CoV-2 (controls). The results showed that significantly more children who experienced SARS-CoV-2 infection had three or more symptoms compared to controls.
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Expert consensus process
Through a consensus process, a multi-disciplinary group of 27 experts from around the world approved the clinical definition for Long COVID in children. This expert panel included researchers, clinicians, patient advocates, WHO staff and others. It was also balanced across gender, region, race, ethnicity and expertise.
To develop this definition, the WHO adopted a two-phase Delphi technique which was also used for the Long COVID definition in adults. This consensus-seeking approach is widely used in health care and helps to bring together knowledge from experts like researchers or clinicians, and sometimes from those affected. Typically, participants in the Delphi process respond to several rounds of questions and the ultimate result is general agreement among members of the expert panel.
145 million people developed Long COVID in the first two years of the pandemic
The Institute for Health Metrics and Evaluation (IHME) estimated that by the end of 2021, nearly 145 million people around the world had developed Long COVID. Most of them suffered from any of the following symptoms: fatigue with bodily pain and mood swings, cognitive problems and shortness of breath. Of these 145 million people, 22 million had symptoms that remained for 12 months after the beginning of COVID-19. In Europe alone, more than 17 million people had Long COVID with symptoms lasting for at least three months after infection with SARS-CoV-2. Altea previously presented this IHME report in detail.
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