A pre-print study from South Africa, published on Tuesday, has found that the risk of being hospitalised with Omicron is just a fifth of the risk with Delta. The study looked at all probable Omicron infections in the country between October 1st and December 6th, and took into account factors associated with hospitalisation such as vaccination status and age. It found that the adjusted risk of being admitted to hospital with probable Omicron infection (defined as S-gene dropout, SGTF) compared to non-Omicron infection is just 0.2, i.e., a fifth of the risk, or an 80% reduction.
Here are the results as stated in the abstract:
From October 1st through December 6th 2021, 161,328 COVID-19 cases were reported nationally; 38,282 were tested using TaqPath PCR and 29,721 SGTF infections were identified. The proportion of SGTF infections increased from 3% in early October (week 39) to 98% in early December (week 48). On multivariable analysis, after controlling for factors associated with hospitalisation, individuals with SGTF infection had lower odds of being admitted to hospital compared to non-SGTF infections (adjusted odds ratio (aOR) 0.2, 95% confidence interval (CI) 0.1-0.3). Among hospitalised individuals, after controlling for factors associated with severe disease, the odds of severe disease did not differ between SGTF-infected individuals compared to non-SGTF individuals diagnosed during the same time period (aOR 0.7, 95% CI 0.3-1.4). Compared to earlier Delta infections, after controlling for factors associated with severe disease, SGTF-infected individuals had a lower odds of severe disease (aOR 0.3, 95% CI 0.2-0.6).
The researchers say the reduction in severity is likely in part to be a result of high population immunity, a factor which would also apply to the U.K after several waves of Covid.
The study confirms the findings from Denmark of a 60% reduction in hospitalisation risk.
Meanwhile, reported infections in Gauteng province continue to decline.
Nonetheless, SAGE continues to make the case for restrictions – and Boris continues to listen.
Read the full study here.
Stop Press: Imperial College London has published a pre-print study on early Omicron hospitalisation rates in England estimating that, compared to Delta, infection with the Omicron variant has a reduced risk of serious illness (defined in terms of a certain length of hospital stay) of 40-45%.