The debilitating effects of long COVID among children may be undercounted and misdiagnosed due to a lack of well-designed longitudinal studies as well as kids' inability to report symptoms properly, according to experts.

Long COVID is an often debilitating illness that reportedly occurs in at least 10 per cent of patients after a COVID-19 infection and includes fatigue, brain fog, headaches, chest pain, and heart palpitations.

While COVID has had less impact on children, some had serious illnesses due to the infectious disease.

According to experts, research on long COVID in children is limited, and reported prevalences range widely, from less than 1 per cent to 70 per cent, CIDRAP News reported.

"I think it's largely because we're trying to apply the adult framework to paediatric problems, and as a result, a lot of things are missed," David Putrino, director of rehabilitation innovation for the Mount Sinai Health System in New York, was quoted as saying to CIDRAP News.

In July, a systematic review of 31 studies published in Pediatrics journal involving 15,000 children concluded that 16 per cent of children had persistent symptoms 3 months after infection.

Another systematic review by the US CDC found that 1.3 per cent of US children ever had long COVID and that 0.5 per cent had it in 2022.

The experts said that many children likely aren't diagnosed as having long COVID because they don't recognise or have the vocabulary to report their symptoms.

"Kids don't come home and say, 'Mom, I have post-exertional malaise, I have brain fog'," Ziyad Al-Aly, a clinical epidemiologist at Washington University in St. Louis was quoted as saying to CIDRAP News.

"What happens is that they start doing poorly in school, and parents find out weeks and weeks later," he noted.

Further, the experts noted that many long-COVID symptoms are subtle and can be misattributed to other conditions, such as anxiety. And unlike the fatigue, brain fog, and post-exertional malaise that adults most often report, Putrino said the most common presentation of long COVID in children seen is recurrent stomach aches, the report said.

"Often, it's not initially thought of as long COVID," he said. "It's just 3 months after a COVID infection, your child's complaining of a tummy ache."

So far the studies done on long COVID in children have been limited by small sample size, reliance on parental surveys rather than interviews, lack of controls, short duration, poor design, and false assumptions about children's viral loads and antibody responses, experts said.

Putrino called for the need for “detailed longitudinal studies where we really take the time to characterise what long COVID looks like in a paediatric population."

In the meantime, he urged "infection prevention." "It's really easy to clean air, it's really easy to put HEPA (high-efficiency particulate air) filters in classrooms, it's really easy to use UV (ultraviolet) lights," he said.