Children with COVID-19 are less likely to suffer from long-lasting symptoms than adults with the infection, a new UK study has shown.
In the study led by King’s College London, researchers found that children with symptoms of COVID-19 typically started to recover after six days, with only 4.4% of these children still experiencing symptoms after four weeks.
The findings have been published in The Lancet Child & Adolescent Health journal.
Researchers analysed data reported by parents and carers through the ZOE COVID Study app. The study offers the first detailed insight into COVID-19 infection in symptomatic school-aged children and provides reassurance that long-term symptoms are rare.
Professor Emma Duncan, lead and senior author of the study, from King’s College London, UK, said: “It is reassuring that the number of children experiencing long-lasting symptoms of COVID-19 symptoms is low. Nevertheless, a small number of children do experience long illness with COVID-19, and our study validates the experiences of these children and their families.”
Symptoms lasted for six days on average
The data used by researchers involved over 250,000 UK children from the ages of five to 17. The team did not collect data regarding school attendance. To measure the length of symptoms of COVID-19 in children, the researchers focused on reports collected between 1 September 2020 and 22 February 2021. Around 1,734 children developed symptoms of COVID-19 and received a positive PCR test result close to the onset of symptoms, with their symptoms reported regularly until they were healthy again. Researchers could then accurately attribute these children’s symptoms to COVID-19 and assess illness duration robustly. Overall, these children were ill for an average of six days and experienced an average of three symptoms in the first week of illness.
Most children recovered from the illness within four weeks, with only a small number (77 out of 1,734) still experiencing symptoms after a month. On average, these children only had two symptoms remaining after four weeks. The most common symptom experienced by children with long-lasting illness was fatigue. 65 out of 77 children were reported with fatigue at some point in their illness, and this was the most persistent symptom. Headache and loss of sense of smell were also common, (each symptom was experienced by 60 out of 79 children at some stage over the course of their illness). However, headache was more common early in illness, while loss of sense of smell tended to occur later and to persist longer.
Of the 1,379 children who developed symptoms at least two months before the end of the study period (on or before 29 December 2020), fewer than 2% experienced symptoms for longer than eight weeks.
Older children were typically ill for longer than primary school aged children (average illness duration seven days in children aged 12 to 17 years compared to five days in children aged five to 11 years). Older children were also more likely to have symptoms after four weeks than younger children (59 out of 1,146 children aged 12 to 17 years compared to 18 out of 588 children aged five to 11 years), but there was no difference in the numbers of children who still had symptoms after eight weeks.
Dr Erika Molteni, first author of the study, from King’s College London, said: “We found that nearly a quarter of symptomatic children testing positive for SARS-CoV-2 during the UK’s second wave did not report core symptoms, suggesting the UK testing policy needs reconsideration.”
Importantly, the researchers also assessed the children who tested negative for COVID-19 who may have had other childhood illnesses, such as colds and flu. To do this, they randomly selected a group of age-matched and gender-matched children with symptoms reported through the app who were tested at the same time as the positive children.
Children with COVID-19 were ill for longer compared to children with other illnesses who tested negative for COVID-19 and were more likely to be ill for more than four weeks with COVID-19. However, at four weeks, the small number of children with other illnesses tended to have more symptoms than those who were ill with COVID-19 (average of five symptoms in COVID-negative group compared to two symptoms in COVID-positive group).
Dr Michael Absoud, a senior author of the study and Consultant & Senior Lecturer at King’s College London, said: “Our data highlight that other illnesses, such as colds and flu, can also have prolonged symptoms in children and it is important to consider this when planning for paediatric health services during the pandemic and beyond. This will be particularly important given that the prevalence of these illnesses is likely to increase as physical distancing measures implemented to prevent the spread of COVID-19 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.”
Study limitations
The authors note some limitations to their findings, including that they could not cross-check the symptoms reported by parents and carers with health records (noting that most children were managed in the community), and there may be inconsistencies in the way people interpret symptoms on behalf of their children. Crucially, only children who had an adult participating in the COVID Symptom Study were able to participate, which may bias participation towards certain demographic groups.
Researchers also highlight that their findings on the number of children experiencing prolonged symptoms are lower than the most recent figures from the UK Government’s Office for National Statistics (ONS). They say this may be because of differences in the way the two studies define the end of COVID-19 illness. The current study also allowed for children to have relapsing and remitting symptoms (allowing for periods of up to a week of being completely healthy). When the ONS used similar cut-offs, the differences between the figures reported here and the ONS data were quite similar. Additionally, ONS estimates are based on data collected monthly, which relies on individuals remembering details of when symptoms were experienced, whereas the COVID Symptom Study collects data in real time.
Professor Emma Duncan added: “We hope our results will be useful and timely for doctors, parents, and schools caring for these children – and of course the affected children themselves.”
