Children and adolescents who test positive for Covid-19 are far more likely to report lingering symptoms three months after infection than those who test negative, according to a new study published in The Lancet Child & Adolescent Health. Here's how many Covid-positive young people continue to experience lingering symptoms—and the symptoms most commonly reported. 

Recovery clinics for Covid-19 long-haulers

Long Covid in children and adolescents

Although there have been several studies on the prevalence and effects of long Covid on adults, comparatively few studies have focused on the effects of the condition of children and adolescents, Nature reports. One of the most comprehensive studies on long Covid in younger people is the Children & Young People with Long Covid (CLoCK) study by researchers at the University College London (UCL) Great Ormond Street Institute of Children Health.

For the CLoCK study, researchers assessed 6,804 adolescents ages 11-17 in the United Kingdom who received Covid-19 PCR tests between January and March 2021. Of the participants, 3,065 had tested positive for Covid-19 and 3,739 tested negative.

At the time of testing, researchers found that 35.4% of participants who tested positive reported symptoms compared with 8.3% of those who tested negative. Similarly, 30.5% of test-positive participants reported three or more symptoms compared with 6.2% of test-negative participants.

Three months after their tests, 66.5% of participants who tested positive for Covid-19 reported having symptoms compared with 53.3% of those who tested negative. In addition, almost twice as many participants who tested positive (30.3%) reported still experiencing three or more Covid-19 symptoms compared with those who tested negative (16.2%). The most commonly reported symptoms among those who tested positive were tiredness (39%), headache (23.2%), and shortness of breath (23.4%).

"Long Covid seems to be a condition where multiple symptoms are very common," said Terence Stephenson, the Nuffield professor of child health at UCL Ormond Street Institute of Child Health and the study's lead author.

According to Nature, the CLoCK study's results suggest that tens of thousands of children and adolescents are affected by long Covid, just in the United Kingdom alone. According to estimates from the U.K. Office for National Statistics, around 44,000 children ages 2-11 and 73,000 adolescents ages 12-17 have long Covid.

The future of long Covid research and treatment

Stephenson said long Covid treatments should be holistic, claiming, "It may be that for some [people with long Covid] you need to be referred on to someone very specialist, but … it's not going to be one magic bullet, one drug, or one therapy that's going to help … People are probably going to need a spectrum of inputs to help them."

He added, "If you have a mixture of symptoms of headache, cough, and dizziness, you probably want to go to a service that can deal with you holistically with all your symptoms."

Separately, the researchers behind the CLoCk study also led a panel of experts, which included clinicians, researchers, and patients, to develop a standardized research definition for long Covid in children and young people.

Using 49 initial statements derived from existing research and data, the panel determined that long Covid in patients ages 2-24 includes symptoms that:

• Develop or continue after testing positive for Covid-19, with at least one being physical
• Affect individuals' physical, mental, or social well-being
• Interfere with some aspect of daily life, including school, work, or relationships
• Persist for at least 12 weeks after initial Covid-19 testing

Overall, the researchers said that their finalized long Covid definition for children and adolescents is "comparable to clinical case definition [of long Covid] in adults proposed by [the World Health Organization]."

Currently, further research into long Covid continues to be underway, Nature reports. For example, the National Institutes of Health has set aside $1 billion to research long Covid, and one study plans to track the recovery of a 'metacohort' of 40,000 adults and children infected with the coronavirus. Separately, the National Institute for Health Research in the United Kingdom is currently funding a study to analyze how families are affected by long Covid, as well as a study of how people's immune systems are affected by the condition.

According to Nature, going forward, "[i]nstitutions and funding agencies need to think harder and more creatively [about how to include children in long Covid research], otherwise children with conditions such as long Covid will continue to be left behind." (Nature, 2/8; Iacobucci, BMJ, 2/8; Walker, MedPage Today, 2/7; Stephenson et al., The Lancet Child & Adolescent Health, 2/7)