Since the coronavirus outbreak began, scientists have been trying to understand why children with COVID-19 are much less likely than adults to experience severe complications from the infection.

To get a “better clinical picture” of how virus can behave in children, a team of researchers at UT Health San Antonio compiled an analysis and review of 131 studies from 26 countries that looked at how COVID-19 affects infants, children, and teens up to 18 years of age.

By understanding which variables and predictors lead to better outcomes in children, the medical community can try to optimize them and devise a treatment that might work for adults, said Dr. Alvaro Moreira, the study’s senior author and assistant professor of pediatrics at UT Health San Antonio.

Published Friday in EClinicalMedicine, an open-access journal from the medical journal The Lancet, the analysis found that the majority of children experience mild symptoms of COVID-19 and recover easily and that severe forms of the disease in children occur only in very rare circumstances.

Those who experienced severe symptoms or developed multisystem inflammatory syndrome – a condition linked to COVID-19 when different body parts become inflamed, including the heart, lungs, kidneys, and brain – had low levels of a white blood cell component called lymphocytes, which are responsible for carrying out immune defense. 

“COVID-positive children who didn’t have the extreme form of the disease had [an average of] 42 percent lymphocytes in their blood, versus 11 percent in children with the multisystem syndrome,” Moreira said. “This parallels what we are seeing in adult patients with poor outcomes.”

Of the 7,780 patients included in the 131 studies analyzed by Moreira’s team, 19 percent showed no symptoms of COVID-19, 21 percent exhibited patchy lesions on their lungs, and nearly 6 percent suffered from co-infections such as flu on top of COVID-19. Similar to adult patients, the symptoms children experienced most were fever and cough, found in 59 percent and 56 percent of children, respectively. 

Symptoms in children are important to study, with school around the corner and decisions that need to be made about in-person versus online instruction, Moreira said. “Young children going back to school are going to be a bit more challenging to contain because they are not at an age where they necessarily understand the importance of just wearing a mask and may take it off.”

And because of flu co-infections and the lag time before symptoms appear, COVID-19 might be more difficult to diagnose, and children might go on to infect others, he said.

“Compiling what we know from the concerted efforts of the medical community around the world is really what’s going to make a difference to try to control the virus and try to find something that can give us immunity towards it,” Moriera said. “The more we learn about how our bodies respond to the virus, the better decisions we can make.”

Roseanna Garza

Roseanna Garza

Roseanna Garza reports on health and bioscience for the San Antonio Report.