Here is a classic 1990 study of 15 volunteers who were *deliberately* infected with a *different* coronavirus squirted into their nose, with immunity monitored for a year. Immunity reached a maximum at 2 weeks. It had lapsed by a year later. .... 25/
Just published
@NEJM
Prevention of Covid for household contacts with exposure via a single subcutaneous injection: results of a randomized trial of combination monoclonal antibodies shows marked benefit