The Science Behind Why Children Fare Better With Covid-19

To understand why children fare better than adults against Covid-19, said Kevan Herold, a professor of immunobiology and internal medicine at Yale University, imagine the immune system as a medieval fortress. The innate response, which includes mucus in the nose and throat that helps trap harmful microbes, is like the moat, keeping assailants out. Innate immunity also includes proteins and cells that trigger the body’s initial immune response. Dr. Herold likens them to cannonballs launched as the enemy is beginning an invasion. A second line of defense, the adaptive immune system, includes T cells and B cells. The adaptive immune system takes longer to initiate a response, but can remember specific weaknesses of past invaders. Think of them as soldiers preparing for battle inside the fortress, Dr. Herold said. Innate immunity doesn’t have the same kind of memory. It relies on patterns associated with harmful microbes more generally. Immunologists have found that children’s immune systems have higher levels of some innate molecules and increased innate responses compared with adults. Experts including Dr. Herold and his wife, Betsy Herold, a pediatric infectious-disease doctor at the Children’s Hospital at Montefiore in the Bronx, think this is key to helping children better fight off the virus that causes Covid-19.