Few children reported a lengthy illness from COVID-19, and even fewer reported developing “long COVID,” British researchers found using parent-reported symptom data from a smartphone app.
Less than 5% of children reported COVID-19 symptoms for more than 28 days, and less than 2% reported symptoms for over 56 days, according to Emma Duncan, MD, PhD, of King’s College London, and colleagues.
Of those who developed lengthier, “long COVID”-type illness, the most commonly reported symptoms throughout their entire illness were anosmia, headache, sore throat and fatigue, they wrote in the Lancet Child & Adolescent Health.
“A small number of children do experience long illness with COVID-19, and our study validates the experiences of these children and their families,” Duncan said in a statement.
Notably, the study contained data from September 2020 to January 2021, which preceded the arrival in the U.K. of the more infectious Delta variant. With the Delta variant now the predominant strain in the U.S., reports of more children becoming seriously ill with COVID-19 have started to emerge.
Duncan’s group based their research off parent reports from the COVID Symptom Study, which tracked self-reported symptoms through a smartphone app. In this case, parents and caregivers reported children’s symptoms.
Researchers collected data from 258,790 children through this “proxy-reporting” system, 75,529 of which reportedly tested positive for COVID-19. Of these, 1,734 children had both a positive test and illness duration data: 1,146 children ages 12-17, and 588 children ages 5-11.
Children were a mean age of 13, with a near even split among boys and girls. About 13% had asthma. Headache was the most commonly reported symptom (62%) followed by fatigue (55%).
“Brain fog” was added as a symptom to the app in November 2020 and was reported in 11.3% of older children and 5.9% of younger children. Two children reported weakness and one reported tics, but the authors found no serious neurological manifestations reported.
Not surprisingly, median illness duration was longer in older children versus younger children (7 vs 5 days, respectively), as “age correlated with illness duration,” the authors wrote.
While 77 children (4.4%) overall had illness that lasted 28 days or longer, it was significantly more common in older compared to younger children (5.1% vs 3.1%, respectively; P=0.046). Children with lengthier illness had most of their symptoms in the first week they were sick: median symptom burden of 6 in the first week versus 8 over the course of their illness. Beyond 28 days, the median symptom burden was 2.
Of the 25 children (1.8%) with illness past 56 days, the most commonly reported symptoms throughout their entire illness were anosmia (84%), headache (80%), sore throat (80%), and fatigue (76%).
Study limitations included that symptom data from the app was not cross-checked with health records, and that the only data were from children who had access to an adult participating in the COVID Symptom Study, which could limit generalizability.
Co-author Michael Absoud, PhD, also of King’s College London, noted in a statement that the prevalence of these illnesses in children is likely to increase as distancing measures designed to prevent COVID spread are relaxed.
“All children who have persistent symptoms — from any illness — need timely multidisciplinary support linked with education, to enable them to find their individual pathway to recovery,” he said.
The study was supported by Zoe Limited, the U.K. Government Department of Health and Social Care, Wellcome Trust, U.K. Engineering and Physical Sciences Research Council, U.K. Research and Innovation London Medical Imaging and Artificial Intelligence Centre for Value Based Healthcare, U.K. National Institute for Health Research, U.K. Medical Research Council, British Heart Foundation, and Alzheimer’s Society.
Duncan and Absoud disclosed no conflicts of interest.
Several co-authors disclosed being employees of Zoe Limited, which helped run the COVID Symptom Study.