Louise Wallace told a meeting of the North Yorkshire Outbreak Management Advisory Board today that case numbers have been climbing since mid-September with most infections among school children and other young people.
She also said it was "quite unusual" that the county's infection rate had climbed above the England average.
"This is being driven by what we are seeing in terms of cases through education settings," Ms Wallace said.
"We are looking at the data everyday trying to understand any patterns or trends, but from what we can in the terms of the age bandings from the most recent cases, they do seem to be coming from school children and young people."
Schools and colleges returned at the start of September and twice-weekly testing is being used to limit infections, while rules on social distancing and face masks have been scrapped.
Ms Wallace said headteachers were receiving continued support from public health teams and that she was hopeful the increase in infections would ease over the coming weeks.
She said: "We are seeing an increase in the daily rate across North Yorkshire and we are slightly above the England average which is quite unusual as we usually track it or are slightly below.
"But I am hopeful that this will start to settle and fall back in line as the next few weeks go by."
The latest figures show North Yorkshire's weekly infection rate per 100,000 people currently stands at 452 - above the England average of 332.
A breakdown of the numbers shows the Harrogate district has the highest infection rate after this week surpassing its previous record of 534 in July to reach 547.
Elsewhere in North Yorkshire, Selby has the second highest infection rate at 501, followed by Scarborough and Hambleton at 437, Craven at 401, Ryedale at 325 and Richmondshire at 324.
By Jacob Webster, Local Democracy Reporter