21 September 2020 - - The first study comparing the immune responses of adults and children with COVID-19 has detected key differences that may contribute to understanding why children usually have milder disease than adults, US-based Albert Einstein College of Medicine said.

The findings also have important implications for vaccines and drugs being developed to curb COVID-19. The study was published in Science Translational Medicine and was conducted by scientists at Albert Einstein College of Medicine, Children's Hospital at Montefiore (CHAM), and Yale University.

The study involved 60 adult COVID-19 patients and 65 pediatric COVID-19 patients (less than 24 years old) hospitalized at CHAM and Montefiore Health System between March 13 and May 17, 2020; 20 of the pediatric patients had the novel multi-system inflammatory syndrome (MIS-C).

The patients' blood was tested for the presence of several types of immune cells, antibody responses, and the inflammatory proteins, known as cytokines, that immune cells produce.

Children with COVID-19 fared significantly better than adults. Twenty-two adults required mechanical ventilation compared with only five of the pediatric patients.

In addition, 17 adults died in the hospital compared with two of the pediatric patients. No deaths occurred among pediatric patients with MIS-C.

People have two types of immunity, innate and adaptive. Innate immunity, in which immune cells respond rapidly to invading pathogens of all kinds, is more robust during childhood.

Adaptive immunity, the second type of immune response, is more specific and features antibodies and immune cells that target specific viruses or other microbes.

Compared with adult patients, pediatric COVID-19 patients in the study possessed significantly higher levels of certain cytokines associated with the innate immune response.

This suggests that young people's more robust innate response protects them from developing acute respiratory distress syndrome, the hallmark of severe and often fatal COVID-19 cases.

One cytokine in particular, known as IL-17A, was found at much higher levels in pediatric patients than in adults.

Both pediatric and adult COVID-19 patients were found to make antibodies against the coronavirus' spike protein, which the virus uses to latch onto and infect cells.

Those spike-protein antibodies include neutralizing antibodies, which block the coronavirus from infecting cells.

Counterintuitively, the researchers found that neutralising antibody levels in adult COVID-19 patients who died or required mechanical ventilation were higher than in those who recovered--and significantly higher than levels detected in pediatric patients.

As for vaccines, Dr. B. Herold notes that most vaccine candidates for protecting against SARS-CoV-2 infection are aimed at boosting neutralizing-antibody levels.

The paper is titled "Immune Responses to SARS-CoV-2 Infection in Hospitalized Pediatric and Adult Patients."

Albert Einstein College of Medicine is a center for research, medical education and clinical investigation.

During the 2019-20 academic year, Einstein is home to 724 M.D. students, 158 Ph.D. students, 106 students in the combined M.D./Ph.D. program, and 265 postdoctoral research fellows.

The College of Medicine has more than 1,800 full-time faculty members located on the main campus and at its clinical affiliates.

In 2019, Einstein received more than USD 178m in awards from the National Institutes of Health.

This includes the funding of major research centers at Einstein in aging, intellectual development disorders, diabetes, cancer, clinical and translational research, liver disease, and AIDS.

Einstein runs one of the largest residency and fellowship training programs in the medical and dental professions in the United States through Montefiore and an affiliation network involving hospitals and medical centers in the Bronx, Brooklyn and on Long Island.

Montefiore Health System is one of New York's academic health systems and is a recognized leader in providing exceptional quality and personalized, accountable care to approximately three m people in communities across the Bronx, Westchester and the Hudson Valley.

It is comprised of 11 hospitals, including the Children's Hospital at Montefiore, Burke Rehabilitation Hospital and close to 200 outpatient care sites.