Nationwide rates of emergency room visits for babies with Mycoplasma pneumoniae are on track to surpass rates for school-age children, data from the U.S. Centers for Disease Control and Prevention shows, as doctors nationwide are grappling with a surge of "walking pneumonia" cases.

The new figures come from the CDC's National Syndromic Surveillance Program, which gathers data on pneumonia-associated emergency room visits from U.S. hospitals.

While cases had been higher in school-age kids compared to other age groups, rates in babies have surged in recent weeks, and are now tied with older kids. According to the latest CDC data, for the week ending Nov. 2, 7.

6% of emergency department pneumonia cases for babies 0-1 years old and children ages 5-17 years old resulted in Mycoplasma pneumoniae diagnoses. "These diagnoses dropped a little after August, but remained high through early November. Of note, diagnoses among 0–1-year-olds have steadily increased throughout the fall without any subsequent decrease," CDC spokesperson Jasmine Reed said in a statement Tuesday.

During the COVID-19 pandemic, cases largely disappeared. CDC officials had said that this year's wave could be heralding a return to waves of Mycoplasma pneumoniae cases that occurred prior to the pandemic. But this year's trend has also been unusual, since cases had previously been thought to be common only in school-aged kids, not younger children.

"While we are seeing right now that it is presenting as a typical r.