The number of COVID-19 outbreaks in Colorado schools grew again over the past week, adding roughly 900 new infections among students.

But the case rate among school-aged children has improved in recent days, state officials said, as vaccinations begin to flow.

Case rates among 5- to 11-year-olds have been the highest of any age group for weeks. They continue to be, but they’ve dropped in recent days, as cases overall in the state show the earliest signs of a plateau. 

Vaccines for children in that age group were approved earlier this month, and nearly 19% of them have been inoculated thus far. 

Understanding spread within schools is “complex,” Colorado’s chief medical officer Eric France said Wednesday. Transmission there is playing a role — and controlling it now is helping lower the spread — but he said parental behavioral changes are also likely important.

Still, outbreaks in K-12 schools here grew again over the past week. As of Nov. 17, there were 282 active outbreaks in Colorado schools, leading to more than 5,400 cases. On Wednesday, when new outbreak data was released by the state, there were 318 outbreaks and more than 6,200 student infections linked to them.

Cases among staff also increased, from 814 to 933.