HARTFORD, Conn. (WTNH) – Some children’s hospitals around the country are being overwhelmed with patients suffering from respiratory illnesses.

Respiratory Syncytial Virus (RSV) in particular is on the rise, according to the latest data from the Centers for Disease Control and Prevention. Cases have spiked, especially in the Northeast and South.

For the last few weeks, Connecticut Children’s Hospital in Hartford has been over capacity as more and more young children have been admitted for RSV. The hospital is now in talks with the National Guard and FEMA about setting up a tent outside to expand capacity.

“We just don’t have as many critical care beds [for children] as we have adult critical care beds simply because we don’t usually need them,” said Dr. Juan Salazar, physician in chief of Connecticut Children’s Medical Center.

Cases began spiking in early September and rose exponentially, he said, which is something he’s never seen before.

“Our hospital was full,” Salazar said. “Our traditional pediatric in-patient beds, we have three floors with 25 beds in each location, we can expand to 28. All of those were full this morning.”

At Yale New Haven Children’s Hospital, RSV cases in the emergency department nearly doubled in the last week, going from 57 to 106. Thirty children are admitted there for RSV each day. In contrast, they only see 1 to 3 children per day in the emergency department with COVID-19.

Several D.C.-area hospitals have also been at capacity for weeks, the Washington Post reports.

“The fact that you have to look at the parent and say your kid needs ICU-level care but we have no bed for them: That’s a very hard conversation to have,” Sofia Teferi, a pediatrician at MedStar Montgomery Medical Center, told the Post.

NBC News found hospitals in California, Illinois, Massachusetts, North Carolina and Rhode Island were also under strain from an influx in RSV patients.

For most kids, RSV usually causes mild cold-like symptoms, including a runny nose, congestion, and a mild fever. Salazar said it can be much worse for children who are immunocompromised or have a heart defect.

“Why so much in September and October? We don’t know,” Salazar said. “We have theories: herd immunity, immune suppression, and everyone getting it at the same time — it’s the perfect storm at our emergency departments.”

Parents should look out for changes in their children’s breathing, which could be a sign of RSV. Other signs include:

• Fast or short breaths
• Grunting noises
• Chest caving in with each breath
• Skin turning blue or purple due to lack of oxygen. On darker skin, look for changes to lips, tongue, gums and around the eyes

There is no vaccine for RSV, but Salazar encouraged parents concerned about their child to ask their pediatrician about immunoglobulin therapy. For mild RSV cases, recovery typically takes a few days.

With the Connecticut Children’s Hospital already at its max capacity, Salazar also worried influenza could put them over the edge.

“Don’t wait, please,” Salazar said. “Get children vaccinated for flu. It’s something you need to do, it’s very important for their family, and you help children’s hospitals lower the number of kids coming in.”

Salazar said they already have two children hospitalized with the flu, which he says is very unusual for October. He expected flu cases would increase significantly in the coming weeks and over the holidays.