Scientists may have figured out why children less likely to have severe COVID-19 symptoms

HOUSTON, Texas — The more we understand about the coronavirus behind the current pandemic, the more prepared we will be to treat patients. Early on, children seemed far less likely than adults to become severely ill from COVID-19. Until recently scientists didn’t know why. Now, researchers at the University of Texas Health Science Center (UTHealth) and Baylor College of Medicine in Houston suggest that differences in lung physiology and immune function could be the reason.

“We, as physicians, have been challenged with the question of how to treat COVID-19 and we’re learning in real time,” says study co-author Bindu Akkanti, MD, in a university release. “I knew that to figure out the best way to treat adults, we needed to get a team together to get to the bottom of why children were being spared from severe illness related to the virus.”

The team of physicians drew two critical conclusions. First, children’s lungs have fewer of the proteins that SARS-CoV-2, the virus that causes COVID-19, uses as a pathway to infect human cells. Second, a child’s immune system is much better at fighting the virus.

Children have an ACE2 up their sleeve when it comes to COVID

To find the important differences between children and adults, the physicians examined all of the existing evidence explaining how the virus infects cells and how the immune system responds to coronavirus. They noticed important differences between children and adults that explain why younger patients don’t get very sick from the virus.

The study reveals children’s lungs don’t make a lot of a certain protein called ACE2. This protein, which appears in much higher amounts in adult lungs, is exploited by the SARS-CoV-2 virus to infect cells. Less ACE2 means less cells with viruses inside. Children also have more T-cells in their lungs — the cells that fight viruses. These cells come with proteins called IL-10, which makes sure inflammation doesn’t get out of control and damage other cells. 

The team says their collaboration is the reason why they were able to make these important discoveries.

“Collaborations like this between adult and pediatric providers are really important and this disease highlights where we can learn a lot when we compare the way it behaves in younger kids with older people,” explains co-author Matthew Harting, MD. “Even now as we’re learning about effective treatments, we’re seeing younger people handle this disease better than older people. Moving forward, physicians and scientists need multidisciplinary collaboration to continue learning – this is just another step in the right direction to attack this virus.”

These findings are published in the American Journal of Physiology-Lung, Cellular, and Molecular Physiology