• Posted February 26, 2025

Childhood Long COVID Might Be Caused By Lower Blood Flow In Lungs

WEDNESDAY, Feb. 26, Blood flow problems within the lungs could be driving long COVID in some children, according to scans using an advanced form of MRI.

Children and teens with long COVID appear to have significantly reduced blood flow through their lungs, researchers reported in the journal Radiology.

This could cause fatigue -- one of the more common symptoms of long COVID in children – due to lower levels of oxygen distributed throughout the body via the bloodstream, researchers said.

The study’s results might explain why kids with normal breathing still suffer from fatigue related to long COVID, researchers said.

“Parents should understand that their children’s persistent symptoms after COVID-19 may have a measurable physiological basis, even when standard medical tests appear normal,” lead researcher Dr. Gesa Pöhler, a senior physician of diagnostic and interventional radiology at Hannover Medical School in Germany, said in a news release.

Long COVID involves symptoms that develop weeks after a person’s initial COVID-19 infection. These symptoms can persist for months or even years.

The most common symptoms of long COVID in children are chronic fatigue, shortness of breath, headache, heart palpitations and poor concentration, researchers said in background notes.

For the study, researchers turned to a type of imaging scan called phase-resolved functional lung (PREFUL) MRI.

This form of MRI can analyze the movement of air in and out of the lungs, as well as blood flow through the lungs.

Adults with long COVID typically are examined using chest CT scans, but doctors are loath to use the same imaging technology on children because it exposes kids to radiation, researchers said.

MRI scans use magnetic waves and can be performed while a patient breathes freely, making it a more suitable procedure for children, researchers said.

Researchers performed PREFUL MRI scans on 54 patients between 11 and 17 years of age. Half had been diagnosed with long COVID, and the other half were healthy.

Compared to the healthy kids, children and teens with long COVID had reduced blood flow through their lungs, results show.

Furthermore, all but one of these kids with long COVID suffered mainly from fatigue.

“Importantly, the severity of fatigue symptoms correlated with these blood flow changes, suggesting a possible biological basis for the patients’ ongoing symptoms,” Pohler said.

Earlier studies also have observed this reduction in lung blood flow in adults, researchers noted.

They theorize that a person’s initial bout with COVID might cause lasting damage to the tiny blood vessels in the lungs, leading to this reduction in blood flow.

This sort of imaging could help guide the monitoring and treatment of children with long COVID in the future, researchers said.

The findings were published Feb. 25.

More information

The Cleveland Clinic has more on long COVID in kids.

SOURCES: Radiological Society of North America, news release, Feb. 25, 2025; Radiology, Feb. 25, 2025