Maslo C, Friedland R, Toubkin M, et al. - In South Africa, a SARS-CoV-2 variant of concern, Omicron (B.1.1.529), was identified on November 24, 2021, which is designated as responsible for a fourth wave of COVID-19. In this study, hospitalized patients with a positive SARS-CoV-2 test result during the fourth wave were assessed as compared with previous waves.

• Previously three COVID-19 waves were recorded in South Africa from: (1) June to August 2020 (ancestral variant), (2) November 2020 to January 2021 (Beta), and (3) May to September 2021 (Delta).

• The period of reaching 26% positivity rates was identified in the previous waves (wave 1: June 14 to July 6, 2020; wave 2: December 1-23, 2020; wave 3: June 1-23, 2021) and compared with the fourth wave (November 15 to December 7, 2021).

• There were differences in the number of patients treated in the hospitals during the same early period of each wave (2,351 in wave 4 vs maximum 6,342 in wave 3); however, in the first 3 waves, admission to hospital was recorded for 68% to 69% of patients presenting to the emergency department with a positive COVID-19 result compared with 41.3% in wave 4.

• Relatively younger patients required hospitalization during wave 4 (median age, 36 years vs maximum 59 years in wave 3) with a higher proportion of females.

• In wave 4, admission of significantly fewer patients with comorbidities was observed, and there was a lower proportion presenting with an acute respiratory condition.

• Significantly reduced proportion of patients required oxygen therapy and mechanical ventilation.

• Rate of admission to intensive care was 18.5% in wave 4 vs 29.9% in wave 3.

• There was a reduction in the median LOS (between 7 and 8 days in previous waves) to 3 days in wave 4.

• The death rates recorded in wave 1 and wave 3 were 19.7% and 29.1%, respectively; the rate reduced to 2.7% in wave 4.