Whakakihia te rerenga e whai ake nei: Ko te John Snow Memorandum, i whakaputaina i roto i "The Lancet", he whakautu na nga kairangahau 80 e whakahe ana i te huarahi herd immunity o te Great Barrington Declaration. I tapaina tōna ingoa ki a John Snow, te tohunga mate uruta i mahi i te
1854 Ko te pakarutanga o te mate pukupuku o Broad Street, e kii ana ko te whakaaro mo te aukati o te kahui he "he tinihanga kino kaore i te tautokohia e nga taunakitanga putaiao". E whakaae ana ko ngā herenga COVID-19 kua arahi ki te whakawātea, e ātaahua ai taua whakaaro, engari e kī ana "kāore he taunakitanga mō te ārai ārai ārai ki te SARS-CoV-2", e tāpiri ana "kaore te rautaki pēnei e arahi ki te mutunga o COVID-19, engari ka hua ki ngā mate uruta, pērā i te take o te maha o ngā mate hopuhopu i mua i te taenga mai o te kano ārai mate".