Study after study has shown that children are less likely to be infected by the coronavirus than adults, and they are less likely to have serious illness if they do develop COVID-19. The question has been why. In a new study published in the journal Nature Communications, researchers analyzed blood samples from 48 children and 70 adults who lived in households in Melbourne, Australia, and who were infected with, or exposed to, the coronavirus. The researchers found that compared to the adults, kids exposed to the virus had infection-fighting immune cells migrate quickly to infection sites, clearing the virus before it had a chance to take hold. In other words, children have a stronger immune response to the virus than adults.