A tale of two waves: Characteristics and outcomes of COVID-19 admissions during the omicron-driven 4th wave in Cape Town, South Africa and implications for the future.

ABSTRACT

Objectives: We aimed to describe the pattern of admissions during the fourth wave of COVID-19 to inform future public health policies. Methods: This was a retrospective descriptive study of an early cohort of all adult patients admitted to a tertiary hospital in Cape Town, South Africa, with SARS-CoV-2 infection at the start of the country's fourth wave. This was compared to an early cohort from the first wave at the same institution. Results: We included 121 SARS-CoV-2 positive admissions from the fourth wave. Thirty-one (25.6%) patients had COVID-19 pneumonia, while 90 (74.4%) had incidental SARS-CoV-2 infection. In the first wave all 116 patients had COVID-19 pneumonia. Thirty-two (26.4%) patients self-reported complete or partial COVID-19 vaccination, of whom 12 (37.5%) were admitted with COVID-19 pneumonia. Compared to the first wave, there were fewer intensive or high care admissions (18/121 [14.9%] vs 42/116 [36.2%], p<0.001) and lower mortality (12/121 [9.9%] vs 31/116 [26.7%], p=0.001). Conclusion: Admissions to the COVID-19 wards during the fourth wave primarily included patients with incidental SARS-CoV-2 infection. There was a reduction in the need for critical care and in-hospital mortality. This changing epidemiology of COVID-19 admissions may be attributed to a combination of natural and/or vaccination-acquired immunity.