Most children are unaware they have Covid-19, which is leading to an over-estimation of the long-term effects of the illness in youngsters, a leading expert has said.

Dr Shamez Ladhani, a consultant paediatrician in infectious diseases and a Public Health England (PHE) epidemiologist, said most children either do not have any symptoms when they have coronavirus, or the illness is so mild their parents do not link it with Covid.

He tweeted: “In our primary schools study, although small numbers, parents reported no symptoms in 85% of kids who didn’t have (Covid) antibodies at start of the study & then developed antibodies during the study (ie. got infected) compared to 47% of staff.

“In secondary schools too, although small numbers again, 67% of students who seroconverted (got infected & developed Covid antibodies) during the study reported having no symptoms at all compared to 24% of staff.”

He also pointed to research suggesting that children’s antibody response to Covid is the same, whether they have experienced symptoms or not.

“Also, some kids appear to have T cell (cellular) immunity against (Covid) even without antibodies against the virus,” he added.

“We think this might reflect cross-protection from previous coronavirus infections, but this needs further work for confirmation.

“So, when trying to estimate risk of severe #COVID19 or #LongCovid, remember that most kids do not even develop any symptoms after virus exposure & some kids may be inherently protected from cellular immunity.

“Surely these kids can’t be at risk of severe or long Covid.”

Experts have disagreed on the extent to which children suffer long Covid, with some arguing the evidence is too limited to offer a clear picture.

Earlier this year, data from the Office for National Statistics (ONS) suggested that 13% of under-11s and about 15% of 12-to-16-year-olds were experiencing at least one symptom five weeks after they tested positive for Covid-19.

A study earlier this month found that the overall risk of children becoming severely ill or dying from Covid is extremely low.

Data from the first 12 months of the pandemic in England showed that 25 under-18s died from Covid, with the highest risk among those with multiple chronic illnesses and neuro-disabilities.