Trends in Cases, Hospitalizations, and Mortality Related to the Omicron BA.4/BA.5 Subvariants in South Africa. (1st December 2022)

• Record Type: Journal Article
• Authors: Jassat, Waasila; Abdool Karim, Salim S; Ozougwu, Lovelyn; Welch, Richard; Mudara, Caroline; Masha, Maureen; Rousseau, Petro; Wolmarans, Milani; Selikow, Anthony; Govender, Nevashan; Walaza, Sibongile; von Gottberg, Anne; Wolter, Nicole; Terrence Pisa, Pedro; Sanne, Ian; Govender, Sharlene; Blumberg, Lucille; Cohen, Cheryl; Groome, Michelle J
• Is Part Of: Clinical infectious diseases. Volume 76:Number 8(2023)
• Page Start: 1468
• Page End: 1475
• Publication Date: 2022-12-01
• Subjects: COVID-19 -- hospital admissions -- mortality -- Omicron BA.4 -- Omicron BA.5; Communicable diseases -- Periodicals; 616.905
• DOI: 10.1093/cid/ciac921
• Languages: English
• ISSNs: 1058-4838

Abstract

Abstract: Background: In this study, we compared admission incidence risk and the risk of mortality in the Omicron BA.4/BA.5 wave to previous waves. Methods: Data from South Africa's SARS-CoV-2 case linelist, national COVID-19 hospital surveillance system, and Electronic Vaccine Data System were linked and analyzed. Wave periods were defined when the country passed a weekly incidence of 30 cases/100 000 population. In-hospital case fatality ratios (CFRs) during the Delta, Omicron BA.1/BA.2, and Omicron BA.4/BA.5 waves were compared using post-imputation random effect multivariable logistic regression models. Results: The CFR was 25.9% (N = 37 538 of 144 778), 10.9% (N = 6123 of 56 384), and 8.2% (N = 1212 of 14 879) in the Delta, Omicron BA.1/BA.2, and Omicron BA.4/BA.5 waves, respectively. After adjusting for age, sex, race, comorbidities, health sector, and province, compared with the Omicron BA.4/BA.5 wave, patients had higher risk of mortality in the Omicron BA.1/BA.2 wave (adjusted odds ratio [aOR], 1.3; 95% confidence interval [CI]: 1.2–1.4) and Delta wave (aOR, 3.0; 95% CI: 2.8–3.2). Being partially vaccinated (aOR, 0.9; 95% CI: .9–.9), fully vaccinated (aOR, 0.6; 95% CI: .6–.7), and boosted (aOR, 0.4; 95% CI: .4–.5) and having prior laboratory-confirmed infection (aOR, 0.4; 95% CI: .3–.4) were associated with reduced risks of mortality. Conclusions: Overall, admission incidence risk and in-hospital mortality, which had increased progressively in South Africa's first 3 waves, decreased in the fourth Omicron BA.1/BA.2 wave and declined even further in the fifth Omicron BA.4/BA.5 wave. Mortality risk was lower in those with natural infection and vaccination, declining further as the number of vaccine doses increased. Abstract : Admission incidence risk and in-hospital mortality decreased in the Omicron BA.1/BA.2 wave, reducing even further in the Omicron BA.4/BA.5 wave. Mortality risk was lower in those with natural infection and vaccination, declining further as the number of vaccine doses increased.