The data, up to 14 November, shows this younger age group has overtaken older, secondary school aged children for the first time.
In recent months, the 10 to 19 age group maintained the highest rate of infections per 100,000 tested.
It is too soon to say what is behind the change and if it will continue.
In recent weeks, children aged 12 and over have started being offered Covid jabs.
The UK Health Security Agency (UKHSA) report shows 723 cases recorded per 100,000 among children aged five to nine.
That’s up week-on-week from 484.5 per 100,000.
The rate for 10 to 19-year-olds is 694.2, up from 571.7.
Covid infections are lowest among the eldest in society – those aged 80-plus – with a weekly rate of 76 per 100,000. But this group has the greatest risk of getting more seriously ill with Covid if they were to catch it, particularly if they are not vaccinated.