New England Journal of Medicine
April 7, 2022 Vol. 386 No. 14
https://www.nejm.org/toc/nejm/medical-journal

Original Articles
Population Immunity and Covid-19 Severity with Omicron Variant in South Africa S.A. Madhi and Others
Widespread underlying SARS-CoV-2 seropositivity was observed in Gauteng before the omicron-dominant wave of Covid-19. Epidemiologic data showed a decoupling of hospitalizations and deaths from infections while omicron was circulating.