It may be three years since the start of the pandemic, but Long Covid is continuing to impact the health of children all over the world.

In July 2022, an international study conducted in eight countries and published in the journal JAMA Network Open estimated the prevalence of Long Covid in children, 90 days after their initial infection, to be anywhere from five to 10 percent.

The study included 1,884 children with COVID-19 who had 90-day follow-up visits. Long Covid was found in nearly 10 percent of hospitalized children and 5 percent of children discharged from the emergency department.

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Should I worry about Long Covid?

Long Covid is defined by the World Health Organization as "the continuation or development of new symptoms three months after the initial infection, with these symptoms lasting for at least two months with no other explanation."

But how exactly do you know if your child has Long Covid? And what can doctors and parents do to treat and support children suffering with symptoms long after their initial illness?

What happens when children have Long Covid?

Lasting anywhere from four weeks to many months, symptoms of Long Covid in children vary widely between age groups and can affect all ages, including babies.

They can range from the comparatively mild symptoms – including a continuous cough, a sore throat, slight dizziness, aches and pains, and changes to smell or taste (more common in adolescents, according to researchers) – to much more severe indicators such as chronic fatigue, recurring chest pains, labored breathing, and "brain fog," where children's thinking becomes sluggish and fuzzy. 

Mental health issues, particularly among adolescents, have also been reported, while rare diagnoses of Multisystem Inflammatory Syndrome in Children, a debilitating condition that attacks the organs, and increased risk of type 1 diabetes have also been linked to the virus in children. Essentially, from the lightest to the most extreme, all of these symptoms could effectively fall under the definition of Long Covid.

Add the complications that few children actually seek medical attention for Long Covid, and it's easy to understand why the difference in the type and duration of symptoms has led to a slew of definitions for Long Covid in younger people.

How common is Long Covid among children?

Even with a working research definition, recording and quantifying the prevalence of Long Covid among children has proven incredibly difficult for researchers.

One of the first studies on Long Covid in children, an Italian report carried out in late 2020, said more than half of the infected children they studied had at least one coronavirus symptom lasting more than 15 weeks.

A more recent study from the University College London of a larger group of children put the figure much lower, with up to one in seven children – just 14 percent – still showing symptoms 15 weeks later. 

The study published in the JAMA Network Open, which included study participants from eight countries: Argentina, Canada, Costa Rica, Italy, Paraguay, Singapore, Spain and the United States, estimated prevalence to be anywhere from between five and 10 percent.

The same study also highlighted three common characteristics associated with Long Covid: Initial hospitalization of 48 or more hours; four or more symptoms at the initial emergency department visit; and the child being aged 14 or older.

What causes post-COVID symptoms in children?

While it is still unclear which children are most likely to be affected by Long Covid, support group Long Covid Kids say that risks appear to be higher for those in the following groups: females; those who are young, fit, and healthy; people with eczema, asthma or hay fever; those allergic to animals; people with previous post viral fatigue; and those with Ehlers-Danlos syndromes, fibromyalgia, or Irritable Bowel Syndrome.

Studies also indicate that generally, the virus is more likely to concentrate in a child's gut than their respiratory system, making their symptoms more gastrointestinal than respiratory. Based on stool samples from children who have had coronavirus, some scientists believe it may take longer for it to exit a child's system than it does for an adult. Such long-term exposure to the viral antigens could lead to regular or intermittent inflammation, even if it is mild. This hypothesis has been dubbed the "slow burn" theory. 

Another theory suggests that Long Covid is a type of autoimmune process in which antibodies made against the virus attack the host even after it has left the body. But despite ever more data from a growing body of studies into the condition, scientists are yet to confirm its root causes in adults or in children. 

How can you treat Long Covid in children and how long will it last?

For those already experiencing Long Covid, the sheer variety of symptoms mean there is no singular method of treating children, but pediatricians from Yale University say the best results tend to come from considering each symptom by itself. 

For example, a child with "brain fog" may be sent to a neurologist, while a young person suffering from exhaustion may go to see a specialist who works with people suffering from diseases linked to chronic fatigue like mononucleosis or 'mono.' It essentially depends which part of the body the virus attacks. 

A large study published in the British Medical Journal says vaccines may also help to lessen Long Covid symptoms in some adults, but more data is needed before any firm conclusions can be drawn and there is no empirical evidence yet that it has the same impact on children.

As for the exact duration of Long Covid, there is no definitive answer, but there is reassuring evidence that symptoms will get better over time in the majority of cases. Still, David Strain, chair of the British Medical Association board of science and a contributor to the new working definition of Long Covid in children, stressed the importance of catching the condition quickly. 

"A three-month delay in offering support to a child or young person, at this vitally important period of their educational development could have lasting long term impacts," he said.

How can parents help children suffering with Long Covid?

The University of Manchester has published guidance from two parents supporting their own children through their Long Covid illness. Their advice includes six key areas they say has helped to support the physical and mental wellbeing of their children.

1. Believe your child

Long Covid is an invisible illness meaning children can look well, but sending them to school while ill could risk worsening their symptoms.

2. Resting and pacing

Work with your children to consider how much energy different activities require (you might categorize activities into low-, medium- and high-energy) and ensure that each activity is followed by rest, particularly those that expend more energy. Even activities such as watching television or scrolling through social media can drain their energy reserves.

3. Seek support at school

Some children with Long Covid may have cognitive impairment (also called "brain fog"), sensitivity to lights or sounds, and fatigue – all of which present barriers to learning at school. Speaking to teachers can help to adapt and optimise their learning environment.

4. Mental health

Spend time emphasising what your children can still do, setting realistic goals, celebrating wins, and trying not to grieve too much over what has been lost.

5. Non-medical treatments

Many people have an overactive "fight or flight" response after viral infections, including COVID-19, due to effects on their autonomic nervous system. This can impact heart rate and blood pressure, as well as gut and bladder function. Reducing screen time and caffeine (particularly in the evenings) and undertaking breathing exercises can help reduce fight or flight hormones.

6. Information and support

Primary care has a key role in supporting young people with Long Covid and their families, including liaising with schools where necessary. So seek the support of your GP.

The Long Covid Kids charity also offers a useful support pack for children and families as well as the opportunity to connect with other kids and families affected by Long Covid.

This story was initially published in February 2022, and substantially updated in March 2023.

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