Compared to the virus that caused the SARS epidemic in the early 2000s, SARS-CoV-2, the virus responsible for COVID-19, has evolved new strategies to bind to cell receptors, resulting in tighter binding. A new study identifies key mutations that potentially enabled the animal-to-human transmission of SARS-CoV-2. The study mapped out important binding sites on SARS-CoV-2 for antibody drugs to act on. If new drugs can bind to the sites on SARS-CoV-2, they will block the virus out of cells.