Scientists at the University of Sydney have discovered a protein in the lung that blocks SARS-CoV-2 infection and forms a natural protective barrier in the human body. Leucine-rich repeat-containing protein 15 (LRRC15) is an inbuilt receptor that binds the SARS-CoV-2 virus without passing on the infection. The discovery opens a new area of immunology research around LRRC15 and suggests a pathway to develop new drugs to prevent viral infection from coronaviruses like COVID-19, but also to deal with fibrosis in the lungs.