Long COVID uncommon in children, analysis finds

In a study published today in Lancet Child and Adolescent Health, researchers at King's College London looked at daily health reports logged in the ZOE COVID Symptom Study app between March 2020 and February 2021 by parents or carers on behalf of more than 250,000 children aged 5-17, with nearly 7,000 having symptoms consistent with COVID-19 and a positive test.

The team previously analysed data from adults using the ZOE COVID Symptom Study, and showed that around one in 7 adults experienced COVID-19 symptoms lasting 4 weeks, while one in 20 were ill for 8 weeks or longer.

For this analysis, the team focused on the period from September 2020 through to February 2021. This coincided with the reopening of schools in the autumn and the peak of the winter wave when there was widespread availability of COVID testing.

During this time, 1,734 children were reported who had a clear start and end point to their symptoms and a positive COVID PCR test, enabling the researchers to determine their duration of illness with some allowance for symptoms reoccurring.

On average, the illness lasted for 5 days in younger children (5 to 11 years old) and 7 days in older children aged 12 to 17. Fewer than one in 20 (4.4%) experienced symptoms for 4 weeks or more, while only one in fifty (1.8%) had symptoms lasting more than 8 weeks.

The most common symptoms reported in children were headaches, tiredness (fatigue), a sore throat, and loss of smell (anosmia). Typically, these children had six different COVID symptoms in the first week, and around eight different symptoms in total over the duration of their illness. Reassuringly, there were no reports of serious neurological symptoms such as fits or seizures, impaired concentration or attention, or anxiety.

The researchers then compared outcomes for the children testing positive for COVID-19 with the same number of age and sex-matched children who were reported as having symptoms in the ZOE COVID Symptom Study app but then tested negative for coronavirus.

On average, these children were ill for only three days, most commonly reporting sore throat, headaches, fever and fatigue. While only a handful of this control cohort had symptoms lasting 4 weeks or more, these children had more symptoms than the children with long illness after COVID-19.

Although the levels of common infectious diseases such as 'flu, respiratory syncytial virus (RSV) and other, coughs and colds have been unusually low during the 2020-2021 winter due to school closures and social distancing, there is a risk that they will bounce back hard over the coming years.

As well as shedding light on the risk of long illness in children with COVID-19, this study also highlights that other childhood infections can cause long-term illness, with implications for the planning and delivery of child health services after the pandemic.

Dr Michael Absoud, a senior author of the study and Consultant & Senior Lecturer from the School of Life Course Sciences, 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."

Health Minister, Lord Bethell said: "Studies like this will help us build our understanding of long COVID and its impact on different groups as we learn to live with the virus. As the Health and Social Care Secretary has said, we want the UK to be a world leader in researching long COVID.

"It's encouraging to see the condition is uncommon among children and we will continue to provide support to those suffering the long term effects of the virus. Already we have opened over 80 long COVID assessment services across England, including specialist services for children and young people backed by £100 million.

"We are also supporting our exceptional scientists with over £50 million for research to better understand the long term effects to ensure the right help and treatments are available."

Senior author Emma Duncan, Professor of Clinical Endocrinology at King's College London, said: "We know from other studies that many children who catch coronavirus don't show any symptoms at all; and it will be reassuring for families to know that those children who do fall ill with COVID-19 are unlikely to suffer prolonged effects. However, our research confirms that a small number do have a long illness duration with COVID-19, though these children too usually recover with time. We hope our results will be useful for doctors, parents, and schools caring for these children -- and of course affected children themselves. It's also important that we remember that there are other infectious diseases that can leave children unwell for many weeks, and these children shouldn't be overlooked."

Professor Tim Spector, ZOE COVID Symptom Study lead, said: "This research highlights the importance of the data that thousands of parents and carers have contributed on behalf of their children. These insights are only possible through large-scale community data science, and we're grateful to everyone who has taken a minute or two out of their busy days to log the health of themselves and their family during the pandemic."