It’s a recurring theme of the COVID-19 crisis: The virus sweeps its way through a community, and, despite being exposed to it in the same place at around the same time, people develop vastly different symptoms. Some barely feel anything — a scratchy throat, if that — while others spend weeks in the ICU with ravaged lungs, unable to breathe on their own.
These scattershot outcomes stem from wide variation in how our bodies respond to the virus. To mount the strongest defense, says Boston Children’s Hospital immunologist Hani Harb, the immune system must maintain a delicate equilibrium. “We need the balance of the force attacking the virus, and at the same time, a counterforce to say, ‘That's enough.’ ”
