The concept of preventing the virus from getting inside a cell is simple. If we can stop the ‘key’ (spike protein) that the virus uses from ever finding the ‘lock’ (ACE2 receptor) by attaching something else to it (drug or antibody), we can stop the virus from ever infecting the cell. Antibodies that bind to the spike protein form naturally in people who recover from infection and should protect these people from a second infection for some time. These are neutralizing antibodies and they are exactly the kinds of antibodies generated by effective vaccines as well.
