The term “herd immunity” first found its way into the UK’s public consciousness very early on in the pandemic. The UK’s chief scientific officer, Patrick Vallance, talked about allowing “enough of us who are going to get mild illness to become immune” and building up “some degree of herd immunity while protecting the most vulnerable”. What Vallance was referring to was herd immunity by natural infection. Without a vaccine this is the only way you can achieve herd immunity—with the attendant illness and death that accompany these natural infections. The idea drew concern from broad swathes of the scientific community and talk of herd immunity as a strategy was subsequently quashed by the government.