Primary school-aged children with long Covid are significantly more likely to have a mental disorder than those without, according to a survey.

The Office for National Statistics (ONS) found pupils from reception to Year 7 suffering long-term effects of the virus were 30% more likely to have at least one probable mental illness.

Parents across the country were sent questions to answer on behalf of their children, with around 1% of primary school pupils estimated to meet the Delphi criteria for long Covid.

The Delphi method defines long Covid as being present if symptoms affecting everyday life continue over a 12-week period or longer.

A total of 8% of primary school-aged pupils were found to have a probable mental disorder and a further 7.6% had a possible mental disorder, according to the figures.

About 30% of children with long Covid presented with a probable mental illness compared with 7.7% without long Covid.

The trend was similar for secondary school pupils – 22.6% compared with 13.6% – but this was not found to be a statistically significant difference.

The ONS added that the analysis does not account for children’s mental health status before having Covid, so causality cannot be inferred.

Around 2.7% of secondary school students met the Delphi criteria for having experienced long Covid and 13.8% overall had a probable mental illness, according to the data.

Among primary and secondary school students, “loss of taste or smell” was the only symptom more prevalent for those with a positive Covid test than those without.

The study also surveyed headteachers about the level of mental health provision in schools, with 87% saying their school had a designated lead for mental health.

Of those with a designated lead, 95% said they felt very or fairly confident that their school was able to implement the activities needed to develop a whole-school approach to mental health.

Lack of time and staff resource pressures were among the reasons listed for not feeling confident in the remaining 5%.