“This is one of the unusual findings and curveballs that this virus keeps throwing at us,” said Dr. Frank Esper, a pediatric infectious diseases specialist at Cleveland Clinic Children’s, whose research focuses on viral respiratory infections and newly recognized infectious diseases. “Normal coronaviruses seem to affect children and adults equally, but this one, for whatever reason, certainly skews more to the adult population.”

The answer may lie in the difference between children’s and adult’s immune systems, said Dr. Vanessa Raabe, an assistant professor in pediatric and adult infectious diseases at NYU Langone. As people age, their immune systems weaken, she said, potentially making it harder for them to fight off illnesses…

There are other possible explanations. Children, who are typically bombarded with certain other coronaviruses, such as the ones that cause the common cold, may have antibodies in their bloodstream from exposure to those that offers some cross-protection for this virus, said Dr. Buddy Creech, an associate professor of pediatric infectious diseases at Vanderbilt Children’s Hospital.