Immune System Clues to Why COVID Is Easier on Kids

Kids and adults have different immune system responses to infection with the new coronavirus, which may help explain why severe COVID-19 is more common in adults, researchers report.

For their new study, they examined blood and cell samples from patients admitted with COVID-19 symptoms to the Montefiore Medical Center in New York City.

The researchers found that the younger the patient, the higher their levels of two immune system molecules, interleukin 17A (IL-17A) and interferon gamma (INF-g).

IL-17A helps trigger immune system response during early infection and INF-g combats replication of the virus. Higher levels of the two molecules may be associated with better outcomes in COVID-19 patients, according to the authors.

“To our surprise, we found these particular serum cytokines were at higher levels in children than adults,” co-senior study author Dr. Kevan Herold, a professor of immunology and internal medicine at Yale University, said in a Yale news release.

Researchers were also surprised to find that certain antibody responses thought to be protective were higher in adults, including those with severe COVID-19, than in children.

IL-17A and INF-g are part of the innate immune system, a more primitive, non-specific response activated early after infection. On the other hand, adults had a more vigorous adaptive immune system response, including higher levels of antibodies that attack the new coronavirus.

The findings suggest “that kids have a more robust, earlier innate immune response to the virus, which may protect them from progressing to severe pulmonary disease,” said co-senior study author Dr. Betsy Herold, a professor of pediatrics and microbiology-immunology at Albert Einstein College of Medicine in New York City.

The study included children and teens with multi-system inflammatory syndrome (MIS-C), a rare complication of COVID-19 infection in young people that’s associated with a range of severe health complications.

Like other youngsters, those with MIS-C also have high levels of IL-17A and INF-g, and rarely develop the severe lung damage seen in adults with severe COVID-19.

The findings suggest that boosting certain types of immune responses may benefit COVID-19 patients, the researchers said.

The study was published recently in the journal Science Translational Medicine.

More information

The U.S. Centers for Disease Control and Prevention has more on COVID-19.

Source: HealthDay