Whether or not a person with COVID-19 develops severe disease depends a lot on how their immune system reacts to the coronavirus. But scientists still don’t know why some people develop severe disease while others suffer only mild symptoms – or no symptoms at all. Now, a new study from Yale University sheds some light on the issue.

Many countries are moving to exit a lockdown triggered by COVID-19, but the virus has not gone away and there are real concerns that a second wave of infection could happen. We urgently need to understand more about how the body deals with this infection and what we can do to tackle it. Immunology has taken centre stage here in revealing what happens when our body fights this virus, and brings us the possibility of treatments and vaccines.