International Journal of Infectious Diseases (Feb 2023)

Outcomes of laboratory-confirmed SARS-CoV-2 infection during resurgence driven by Omicron lineages BA.4 and BA.5 compared with previous waves in the Western Cape Province, South Africa

  • Mary-Ann Davies,
  • Erna Morden,
  • Petro Rousseau,
  • Juanita Arendse,
  • Jamy-Lee Bam,
  • Linda Boloko,
  • Keith Cloete,
  • Cheryl Cohen,
  • Nicole Chetty,
  • Pierre Dane,
  • Alexa Heekes,
  • Nei-Yuan Hsiao,
  • Mehreen Hunter,
  • Hannah Hussey,
  • Theuns Jacobs,
  • Waasila Jassat,
  • Saadiq Kariem,
  • Reshma Kassanjee,
  • Inneke Laenen,
  • Sue Le Roux,
  • Richard Lessells,
  • Hassan Mahomed,
  • Deborah Maughan,
  • Graeme Meintjes,
  • Marc Mendelson,
  • Ayanda Mnguni,
  • Melvin Moodley,
  • Katy Murie,
  • Jonathan Naude,
  • Ntobeko A.B. Ntusi,
  • Masudah Paleker,
  • Arifa Parker,
  • David Pienaar,
  • Wolfgang Preiser,
  • Hans Prozesky,
  • Peter Raubenheimer,
  • Liezel Rossouw,
  • Neshaad Schrueder,
  • Barry Smith,
  • Mariette Smith,
  • Wesley Solomon,
  • Greg Symons,
  • Jantjie Taljaard,
  • Sean Wasserman,
  • Robert J. Wilkinson,
  • Milani Wolmarans,
  • Nicole Wolter,
  • Andrew Boulle

Journal volume & issue
Vol. 127
pp. 63 – 68

Abstract

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Objectives: We aimed to compare the clinical severity of Omicron BA.4/BA.5 infection with BA.1 and earlier variant infections among laboratory-confirmed SARS-CoV-2 cases in the Western Cape, South Africa, using timing of infection to infer the lineage/variant causing infection. Methods: We included public sector patients aged ≥20 years with laboratory-confirmed COVID-19 between May 01-May 21, 2022 (BA.4/BA.5 wave) and equivalent previous wave periods. We compared the risk between waves of (i) death and (ii) severe hospitalization/death (all within 21 days of diagnosis) using Cox regression adjusted for demographics, comorbidities, admission pressure, vaccination, and previous infection. Results: Among 3793 patients from the BA.4/BA.5 wave and 190,836 patients from previous waves, the risk of severe hospitalization/death was similar in the BA.4/BA.5 and BA.1 waves (adjusted hazard ratio [aHR] 1.12; 95% confidence interval [CI] 0.93; 1.34). Both Omicron waves had a lower risk of severe outcomes than previous waves. Previous infection (aHR 0.29, 95% CI 0.24; 0.36) and vaccination (aHR 0.17; 95% CI 0.07; 0.40 for at least three doses vs no vaccine) were protective. Conclusion: Disease severity was similar among diagnosed COVID-19 cases in the BA.4/BA.5 and BA.1 periods in the context of growing immunity against SARS-CoV-2 due to previous infection and vaccination, both of which were strongly protective.

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