• The US Centers for Disease Control reported an increase in pediatric cases of “walking pneumonia”
• There is an increase “every few years,” says Dr. Matthew Isaac Harris, a pediatric emergency medicine physician at Northwell Health in New York, tells PEOPLE
• Dr. Harris said the infection is “very treatable” with antibiotics and advised parents to avoid over-the-counter cough medicines

Cases of atypical pneumonia (also known as “running pneumonia”) — a lung infection caused by the bacterium Mycoplasma pneumoniae — are increasing in the United States, with cases in children increasing so much that the U.S. Centers for Disease Control Control (CDC) issued a warning on Friday, October 18th.

But what exactly is walking pneumonia?

“Running pneumonia is a layman’s term for a type of pneumonia that we refer to in medical terms as atypical pneumonia. “This just means that they (the patients) do not follow the normal course of fever, cough and acute deterioration,” Dr. Matthew Isaac Harris, a pediatric emergency physician and medical director of critical care transport at New York-based Northwell Health, tells PEOPLE.

“They look clinically better than the average case,” he explains, adding that these less severe symptoms can lead to delayed diagnosis.

“You may have a worsening cough for a week to two weeks. “Sometimes it’s a bit of a fever,” says Dr. Harris. “They don't have the classic three- to four-day productive cough with a high fever that you might see in the more classic pneumonia.”

But even though cases are increasing, “this is not a unique year,” the doctor adds. “We have these flare-ups of mycoplasma pneumonia every few years.”

Regarding the reasons for the spread among children, he explains: “They cough constantly in small classrooms, in kindergarten or in playgroups. What puts children at higher risk is just being in contact with other children who are constantly coughing around them.”

“The increase is happening every few years this year,” he explained. “It’s highly contagious.”

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The good news, says Dr. Harris tells PEOPLE that it is “very, very treatable” with antibiotics — generally azithromycin, which, he explained, is “more colloquially known as Z-pack.”

“It's once a day for five days, so this isn't the time where you're dealing with your child trying to get a large amount of antibiotics three times a day,” he tells PEOPLE.

And no matter how quickly your child recovers, “completing the entire course is critical.”

Dr. However, Harris also advises parents to avoid over-the-counter cough medicines.

“Children tolerate honey very well. Honey is a natural cough remedy. I would encourage parents not to use cough medicine on children that has not been approved by their pediatrician.”

Although the CDC has issued a warning, Dr. Harris: “We are in the phase of ‘be careful’.”

“Watch for signs of shortness of breath, which is particularly important in younger children under 2 years of age. Older kids will tell you they’re not feeling well.”

He advised parents to watch for symptoms including “breathing faster, not drinking as much, maybe not peeing as much because they're not drinking.”

“We don’t want parents to run to the pediatrician every time their child coughs,” says the doctor. “It's really just this cough that slowly gets worse and after a week to ten days, a low-grade fever that doesn't get better.” It's really time to see your pediatrician.