TRENDS IN CASES, HOSPITALISATION AND MORTALITY RELATED TO THE OMICRON BA.4/BA.5 SUB-VARIANTS IN SOUTH AFRICA

• DOI: 10.1101/2022.08.24.22279197
• Publication Date: 2022-08-25T17:35:12Z
• Authors: Waasila Jassat; Salim S Abdool Karim; Lovelyn Ozougwu; Richard Welch; Caroline Mudara; Maureen Masha; Petro Rousseau; Milani Wolmarans; Anthony Selikow; Nevashan Govender; Sibongile Walaza; Anne von Gottberg; Nicole Wolter; Pedro Terrence Pisa; Ian Sanne; Sharlene Govender; ; Lucille Blumberg; Cheryl Cohen; Michelle J. Groome
• Keywords: Case fatality rate

ABSTRACT Introduction The Omicron BA.1/BA.2 wave in South Africa had lower hospitalisation and mortality than previous SARS-CoV-2 variants was followed by an BA.4/BA.5 wave. This study compared admission incidence risk across waves, the of wave, to Delta waves. Methods Data from Africa’s national hospital surveillance system, case linelist Electronic Vaccine System were linked analysed. Wave periods defined when country passed a weekly 30 cases/100,000 people. Mortality rates Delta, post-imputation random effect multivariable logistic regression models. Results In-hospital deaths declined 6-fold 37,537 6,074 further 7-fold 837 fatality ratio (CFR) 25.9% (N=144,798), 10.9% (N=55,966) 7.1% (N=11,860) BA.1/BA.2, waves respectively. After adjusting for age, sex, race, comorbidities, health sector province, patients higher (adjusted odds [aOR] 1.43; 95% confidence interval [CI] 1.32-1.56) (aOR 3.22; CI 2.98-3.49) Being partially vaccinated 0.89, 0.86-0.93), fully 0.63, 0.60-0.66) boosted 0.31, 0.24-0.41); prior laboratory-confirmed infection 0.38, 0.35-0.42) associated with reduced risks mortality. Conclusion Overall, in-hospital mortality, which increased progressively first three decreased fourth even fifth those natural vaccination, declining as number vaccine doses increased.