COVID-19 cases in children have hit their highest level since November. Continuing Coverage: Coronavirus in WisconsinIn Milwaukee County, more than one-third of all new cases are in kids under the age of 18.Doctors said the numbers are likely to go even higher. "We've seen an increase in kids testing positive for COVID-19 across our primary care, urgent care, emergency department and in our hospitals themselves," Children's Wisconsin Chief Medical Officer Dr. Michael Gutzeit said.In Wisconsin last week, young people under age 18 accounted for 29% of all new COVID-19 cases.In Milwaukee County, the rate is even higher, 34% or more than one in three new cases involves kids, many of them just two weeks into a new school year and too young to be vaccinated."It's not surprising that we're seeing higher rates of infection in these kids because they really lack the protection that a lot of the other counterparts who are above the age of 12 have," said Dr. Joseph McBride, a pediatric infectious disease specialist at UW Health.The highest number of pediatric cases is in children 9 to 13 years old, but even kids 3 and under accounted for nearly 400 positive cases in the first week of September alone."How concerning are these numbers?" WISN 12's Kent Wainscott asked."Without a doubt, yes, some of these more circulating variants that we're seeing right now, such as the delta variant, does seem to have more severe impacts on the pediatric population," McBride said.Health officials said children are less likely than adults to get a severe illness or be hospitalized, but they worry about where this trend may be headed."Do you expect the numbers to continue to rise?" Wainscott asked."Right now, I think there is evidence pointing that we are still heading up," McBride said.It's been two weeks since Milwaukee Public Schools students returned to class. MPS said 490 students and more than 100 staff have tested positive for COVID-19 since Aug. 30. Sign up for coronavirus email alerts from WISNGet breaking news alerts with the WISN 12 app.Follow us: Facebook | Twitter | Instagram | YouTube