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. They suggest adult patients respond to coronavirus infection with an over-vigorous, but less effective “adaptive” immune response.
“Our findings suggest that children with COVID-19 do better than adults because their stronger innate immunity protects them,” co-senior author Betsy Herold, the chief of infectious diseases and vice chair for research in the department of pediatrics at Albert Einstein College of Medicine and the Children’s Hospital at Montefiore.
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 Einstein, CHAM and Yale University.
People have two types of immunity: innate and adaptive. With innate immunity, which is typically more robust during childhood, immune cells respond rapidly to invading pathogens. 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.
According to the Peter Doherty Institute for Infection and Immunity in Melbourne, Australia: “Coronavirus particles have a corona (crown) of proteins that resemble spikes, which enable the virus to attach and enter cells in humans. The spike protein is crucial in inducing neutralizing antibodies to protect from re-infection.”
“Neutralizing antibodies not only bind to the viral spike protein, but prevent it from being able to attach to and enter human cells. Generating a strong neutralizing antibody response is an important goal for SARS-CoV-2 vaccines,” it adds. “The spike protein is the target for most of the current COVID-19 vaccine human clinical trials.”
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 co-senior author Kevan Herold, a professor of immunology and medicine at Yale School of Medicine.
“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,” a type of serious lung damage now associated with severe 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 phenomenon 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 and led to an inflammation of the lungs and 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 (under 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.
AstraZeneca AZN, -1.20%, in combination with Oxford University; BioNTech SE BNTX, -0.34% and partner Pfizer PFE, +0.01% ; Johnson & Johnson JNJ, -0.46% ; Merck & Co. MERK, -1.34% ; Moderna MRNA, -1.09% ; Sanofi SAN, -3.90% and GlaxoSmithKline GSK, -1.25% are among those currently working toward COVID-19 vaccines.
COVID-19 has killed 965,893 people worldwide, and 200,005 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 (6,861,211), followed by India (5,562,663). Worldwide, there have been 31,389,682 confirmed cases.
Stocks have been on a roller-coaster ride since the pandemic began and as the world awaits vaccines to stop COVID-19. The Dow Jones Industrial Index DJIA, -0.31% was slightly lower Tuesday, while the S&P 500 SPX, +0.10% and the Nasdaq Composite COMP, +0.44% were marginally higher. Monday’s stock-market selloff sets up the worst September in 18 years.