Why do children appear to fight off COVID-19 more effectively than adults?
A new study published Tuesday on the immune response by children and adults to COVID-19, the disease caused by SARS-CoV-2, has important implications for vaccines and drugs being developed to curb the novel coronavirus, according to the researchers.
The study in Science Translational Medicine, an online journal that publishes research at the intersection of science, engineering and medicine, was conducted by scientists at Albert Einstein College of Medicine, the Children’s Hospital at Montefiore, and Yale University.
“Our findings suggest that children with COVID-19 do better than adults because their stronger innate immunity protects them,” co-senior author Betsy Herold, chief of infectious diseases and vice chair for research in the department of pediatrics at Einstein and CHAM.
People have two types of immunity: Innate and adaptive. With innate immunity, immune cells respond rapidly to invading pathogens; it is typically more robust during childhood. Adaptive immunity involves antibodies and immune cells that target specific viruses or other microbes.
Vaccine candidates for protecting against SARS-CoV-2 infection are typically aimed at boosting neutralizing-antibody levels, Herold said. “We may want to consider assessing vaccines that promote immunity in other ways, such as by bolstering the innate immune response,” she said.
What’s more, spike-protein 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 found in pediatric patients, the study found.
These results suggest that the more severe COVID-19 disease seen in adults may not only be caused by a failure of their adaptive immunity to mount T-cell or antibody responses, said Kevan Herold, professor of immunology and medicine at Yale School of Medicine, and co-senior author.
“Rather,” he said, “adult patients respond to coronavirus infection with an over-vigorous adaptive immune response that may promote the inflammation associated with acute respiratory distress syndrome,” which is the hallmark of severe and often fatal COVID-19 cases.”
Doctors and members of the public were spooked by how otherwise strong, healthy people fell victim to the 1918 influenza. Doctors today attribute that to the “cytokine storm” or hypercytokinemia, a process where the immune system in healthy people reacts so strongly as to hurt the body.
A hallmark of some viruses: A surge of immune cells and their activating compounds (cytokines) effectively turned the body against itself, led to an inflammation of the lungs, severe respiratory distress, leaving the body vulnerable to secondary bacterial pneumonia.
The latest study involved 60 adult COVID-19 patients and 65 pediatric COVID-19 patients (less than 24 years old) hospitalized at the Children’s Hospital at Montefiore and Montefiore Health System earlier this year. They were tested for immune cells, antibody responses, and cytokine.
COVID-19 has now killed at least 965,064 people worldwide, and 199,886 in the U.S., Johns Hopkins University says. As of Tuesday, the U.S. still has the world’s highest number of COVID-19 cases (6,857,967). Worldwide, there have been at least 31,343,430 confirmed cases.