Schools in England reopened on Monday, March 8, following the national lockdown, and the latest figures show a sharp increase in the number of secondary school-age children in the city testing positive for coronavirus since then.
That has led to a slight uptick in cases overall in recent days, following a steady fall over preceding weeks.
But Sheffield Council, which shared the data, says this does not necessarily show the virus is spreading within schools as the higher number of cases could be down to the routine testing of pupils taking place.
All children are now being offered regular tests, whether or not they have symptoms, which the council says could mean more cases which would otherwise have gone undetected are being identified.
The council also points out that cases are still falling among people aged 65 and over.
It is important to note too that cases had already started rising among 12 to 17-year-olds in Sheffield before schools reopened.
"We’ve vaccinated over 200,000 people in Sheffield. There’s a definite effect which can be seen in a drop in those hospitalised with Covid – the vaccine reduces the severity of the illness,” said the council in its latest update, issued yesterday evening.
“There may well be increases in rates over the next few weeks as we cautiously reduce the lockdown measures. However, Sheffield’s rates are the lowest in South Yorkshire – what you have been doing to slow the spread has worked. Thank you Sheffield!”