Cases of RSV, flu ticking up among young children in US as respiratory virus season begins

(NEW YORK) -- Cases of flu and respiratory syncytial virus (RSV) are ticking up across the United States even as overall respiratory virus activity remains low.

Flu activity is increasing slightly among children while RSV activity is elevated in the southern, central and eastern U.S., according to data updated Monday from the Centers for Disease Control and Prevention.

As of the week ending Nov. 23, the latest date for which data is available, 0.6% of emergency department visits were for flu and 0.4% were for RSV. While the overall percentages are low, they are higher than the percentages at the beginning of October, CDC data shows.

Meanwhile, about 5.6% of weekly tests are coming back positive for RSV and 2.5% are coming back positive for flu, according to CDC data.

Currently 14 states are experiencing moderate levels of overall respiratory illness: Arizona, Connecticut, Delaware, Georgia, Indiana, Kansas, Kentucky, Louisiana, Maryland, Ohio, Pennsylvania, Texas, Virginia and Wisconsin. The remaining states are seeing low levels.

Dr. John Brownstein, an epidemiologist and chief innovation officer for Boston Children's Hospital and an ABC News contributor, said the current season is trending similarly to pre-pandemic seasons.

"Compared to the pandemic years, we're witnessing a return to more traditional seasonal patterns of respiratory illnesses," he said. "During the pandemic, measures like masking and social distancing significantly reduced the spread of viruses like flu and RSV. Now, with those measures relaxed, the circulation of these viruses resembles pre-pandemic seasons."

He added, "These are typical seasonal increases. Every cold and flu season is different in terms of start, end and severity but, like clockwork, we see a rise in respiratory viruses during the fall and winter months."

Brownstein said it is unsurprising that young children are currently the most impacted by these respiratory viruses.

CDC data shows that children aged 4 and under accounted for 6.7% of emergency department visits for COVID-19, flu and RSV compared to 1.1% among those aged 65 and older during the week of Nov. 23. Children aged 4 and under also had the highest rate of hospitalizations over the same period.

"Managing capacity is going to be on the minds of every pediatric hospital for the next few months," Brownstein said.

The CDC also noted that cases of so-called "walking pneumonia" among young children remain high. The illness is due to a respiratory tract infection caused by the bacteria Mycoplasma pneumoniae.

Brownstein said the best way for Americans to stay protected is to stay up-to-date with their vaccinations.

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

For babies under eight months, there are two monoclonal antibody products available. Monoclonal antibodies are proteins manufactured in a lab that mimic the antibodies the body naturally creates when fighting an infection.

The CDC currently recommends everyone aged 6 months and older receive a flu vaccine and a COVID-19 vaccine.

"Additionally, practicing good hygiene -- like frequent hand washing, covering coughs and sneezes, and staying home when feeling unwell -- can significantly reduce the spread of these viruses," Brownstein said.

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