Since it appeared in 2019, COVID-19 has claimed over 6 million lives and upended society across the globe. The condition, caused by the SARS-CoV-2 virus, attacks cells in the lungs, heart and brain, among other organs. Researchers soon realized that the disease affected these organs so dramatically because its distinctive spikes binded to the angiotensin-converting enzyme 2, or ACE2 receptor. The protein—common in those organs—provides the entry point for the coronavirus to hook into and infect cells.