Schools have opened their doors again, just as the coronavirus delta variant has spread through the state, infecting more children and teenagers.

Across Massachusetts, case counts and hospitalizations among people 19 and younger have continued to rise — with vaccines still yet to be authorized for younger children. And while children are at very low risk for severe illness, infections can disrupt school, force family members to quarantine and put immunocompromised members of households at risk. 

These graphs show just how many kids have been getting sick across the state in the lead-up to the school year — and which age groups. 

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Since April, the state has broken down infections in children by age group.  

Those breakdowns show that the brunt of the virus' impact has shifted somewhat from older children to younger ones. That likely is because kids 12 and older have been eligible for the vaccine for months.

Another way to look at it? Last spring, 15- to 19-year-olds made up almost 40 percent of all COVID-19 cases in children and teenagers.

As of late August, they made up only about 27 percent of all the cases. 

Health experts say it's important to remember that cases in children rarely lead to severe illness and death.

The American Academy of Pediatrics found that, in every state where data was available, fewer than 2 percent of kids testing positive were hospitalized. In many states, that rate was well below 1 percent. 

And, in Massachusetts, these cases come amid a sharp increase in overall cases. 

Francesca Paris can be reached at and 413-447-7311, ext. 239.