ORLANDO, Fla. -

Nemours children's hospital at Lake Nona has only been open a little over a month, but already the patient rooms are filling up.

The occupants share something in common: over half of them are being treated for respiratory synctinal virus, or RSV.

Three-year-old Kylie Pelleymounter is one of them, although WKMG-TV's cameras were not allowed inside her room to meet her.

"She's on what they call contact isolation, so everyone that comes in right now has to gown up and glove up so they won't spread it," said her father, Josh.

Kylie was born premature and Pelleymounter said since she was at risk for an RSV infection they were utilizing a preventative medication called Synagis.

However, when the todller passed her second birthday Blue Cross Blue Shield stopped covering the medication.

"We've sent doctors notes and we send everything in and it's just one of theose things that gets denied," said Pelleymounter.

According to Dr. Livingston, there is no antibiotic or anti-RSV drug onces the virus is contracted so prevention is very important.

RSV starts with symptoms like a common cold but turns into a very aggressive problem that causes inflammation and swelling in the chest, according to Dr. Floyd Livingston.

Livingston is a pediatric pulmonary and sleep specialist for Nemours who treats more RSV infections this time of year than anything else.

According to the Centers for Disease Control, RSV effects children at epidemic levels during the fall and winter months.

Due to the moist climate in the state of Florida, RSV tends to have a longer season here.

The CDC said almost all children will contract the virus prior to 2 years of age, and it is the leading cause of infant hospitalization.

Children who are born premature or with immune deficiencies are most at risk. It's why parents like Rosie Moore take advantage of Synagis while they can.

"I did the research on RSV and the vaccinations far outweighed the risk," said Moore, whose son Caleb spent nearly 5 months in a neo-natal intensive care unit at Florida Hospital.

Now 3 year's old, he is also past the age criteria for Aetna insurance to cover the shots.

Aetna did not respond to requests for comment.

Our sister station, WKMG in Orlando, reached out to Blue Cross Blue Shield, Aetna, Cigna, United Healthcare and Humana to find out each company's policy on covering the drug synagis.

Aetna did not respond.

The other companies all stood by the same policy: they follow the American Academy of Pediatrics guidlines for RSV which indicates that Synagis is not effective in children over the age of two.