Some hospitals in the United States are seeing an increase in RSV and higher levels of “walking pneumonia” in young children, even though overall respiratory disease activity remains low nationally.

Cook Children’s Medical Centers in Texas reported a “sharp increase” in the number of children going to emergency rooms due to respiratory illnesses.

As of Tuesday, at the Fort Worth health system site alone, there were 572 patients — a near-record number — in the emergency department. Officials said the increase in hospital visits is due to a spread of RSV and walking pneumonia in the Dallas-Fort Worth area.

Additionally, University of North Carolina Hospitals reported 40 cases of walking pneumonia in the last week of October, compared to zero cases during the same period last year.

Infectious disease specialists say that while parents should remain vigilant about the spread of respiratory illnesses, this season could also mark a return to typical seasons seen before the COVID-19 pandemic.

“It’s the calm before the storm,” Dr. Peter Chin-Hong, a professor of medicine and infectious disease specialist at the University of California, San Francisco, told ABC News. “It feels like there’s so much going on…that we almost forget about respiratory viruses, but they’re very regular. They’re sort of falling back to a normal pre-pandemic rate.”

Walking pneumonia shows cyclical increase

So-called “walking pneumonia” is a bacterial respiratory tract infection caused by the bacteria Mycoplasma pneumoniae (M. pneumoniae), according to the Centers for Disease Control and Prevention.

Infections are usually mild, and people with a lung infection may seem better than expected, hence the term walking pneumonia, the CDC said. However, sometimes serious complications occur and require hospitalization.

For the week ending November 2, the latest for which CDC data is available, 2.8% of all emergency room visits associated with pneumonia led to an M. pneumoniae diagnosis, compared to just 2% at the end of September .

Rates were highest among people aged 1 year and younger, accounting for 7.8% of all pneumonia-associated emergency room visits with a diagnosis of M. pneumoniae for the week ending November 2.

Experts say mycoplasma infections are cyclical in nature and tend to increase every three to seven years.

“Just like other respiratory viruses, there hasn’t been a lot of exposure during the pandemic years due to social distancing and people staying away from each other, and so we are in the process of catch up,” Chin-Hong said. “Mycoplasma can also be one of those things where you kind of see the perfect storm. So it comes back every four or five years and people go back to their normal lives.”

RSV activity returns to pre-pandemic levels

Respiratory syncytial virus, or RSV, is a common respiratory virus that affects most children by their second birthday, according to the CDC.

Although it usually causes mild, cold-like symptoms and most people recover within one to two weeks, it can be a serious infection for infants and the elderly, leading to hospitalization. the CDC said.

Current levels remain lower than those observed at the same time in recent seasons.

“Although RSV activity is increasing in some areas, particularly among young children, it is important to remember that we are seeing a return to more typical pre-pandemic patterns,” said epidemiologist Dr. John Brownstein. and director of innovation at Boston Children’s. Hospital and ABC News contributor.

“This year, the season starts later and progresses more slowly than previous years, which were marked by earlier and more serious outbreaks,” he added.

Brownstein pointed out that while national levels remain low, some regions in the South and East of the United States are seeing localized surges, particularly among young children.

When to go to the emergency room

Chin-Hong said if symptoms are mild, including low-grade fever, dry cough, sore throat, headache and mild pain, parents can keep their children home and contact their healthcare provider primary for any questions.

However, when symptoms worsen, including difficulty breathing, persistent fever, or lethargy, it may be time to go to the emergency room.

If you have “a child who has been coughing for more than seven days and maybe isn’t getting over it, then you worry about something like walking pneumonia,” Chin-Hong said.

How to prevent RSV and walking pneumonia

To prevent RSV, three vaccines are approved for adults aged 60 and older as well as some adults aged 50 to 59 who are at higher risk. There is also a vaccine available for pregnant women between 32 and 36 weeks gestation.

For babies younger than eight months, two monoclonal antibody products are available. Monoclonal antibodies are laboratory-made proteins that mimic the antibodies the body creates naturally when fighting an infection.

“For walking pneumonia or mycoplasma, there is no vaccine for that, but by getting vaccinated against RSV, COVID (and) the flu, you reduce the likelihood of co-infections that can make things worse.” , said Chin-Hong.

Experts also recommended applying lessons learned during the COVID-19 pandemic, such as wearing a mask in poorly ventilated spaces.

“Practicing good hygiene, such as frequent hand washing and covering coughs and sneezes, remains essential to preventing the spread of respiratory infections,” Brownstein said.