By LAURAN NEERGAARD and CANDICE CHOI Associated Press
Scientists are starting to unravel one of COVID-19’s scariest mysteries: Why are some people only mildly ill or have no symptoms and others rapidly die. An international team of researchers found that in some people with severe COVID-19, the body goes rogue and attacks one of its own key immune defenses instead of fighting the coronavirus. Most were men, helping to explain why the virus is hitting men harder than women. And separate research suggests that children fare better than adults thanks to robust “first responder” immune cells that wane with age.