Clinical severity of COVID-19 patients admitted to hospitals during the Omicron wave in South Africa

Abstract

Background: Clinical severity of patients hospitalised with SARS-CoV-2 infection during the Omicron (fourth) wave was assessed and compared to trends in the D614G (first), Beta (second), and Delta (third) waves in South Africa. Methods: Weekly incidence of 30 laboratory-confirmed SARS-CoV-2 cases/100,000 population defined the start and end of each wave. Hospital admission data were collected through an active national COVID-19-specific surveillance programme. Disease severity was compared across waves by post-imputation random effect multivariable logistic regression models. Severe disease was defined as one or more of acute respiratory distress, supplemental oxygen, mechanical ventilation, intensive-care admission or death. Results: 335,219 laboratory-confirmed SARS-CoV-2 admissions were analysed, constituting 10.4% of 3,216,179 cases recorded during the 4 waves. In the Omicron wave, 8.3% of cases were admitted to hospital (52,038/629,617) compared to 12.9% (71,411/553,530) in the D614G, 12.6% (91,843/726,772) in the Beta and 10.0% (131,083/1,306,260) in the Delta waves (p<0.001). During the Omicron wave, 33.6% of admissions experienced severe disease compared to 52.3%, 63.4% and 63.0% in the D614G, Beta and Delta waves (p<0.001). The in-hospital case fatality ratio during the Omicron wave was 10.7%, compared to 21.5%, 28.8% and 26.4% in the D614G, Beta and Delta waves (p<0.001). Compared to the Omicron wave, patients had more severe clinical presentations in the D614G (adjusted odds ratio [aOR] 2.07; 95% confidence interval [CI] 2.01-2.13), Beta (aOR 3.59; CI: 3.49-3.70) and Delta (aOR 3.47: CI: 3.38-3.57) waves. Conclusion: The trend of increasing cases and admissions across South Africa's first three waves shifted in Omicron fourth wave, with a higher and quicker peak but fewer admitted patients, who experienced less clinically severe illness and had a lower case-fatality ratio. Omicron marked a change in the SARS-CoV-2 epidemic curve, clinical profile and deaths in South Africa. Extrapolations to other populations should factor in differing vaccination and prior infection levels.

Clinico epidemiological profile of Omicron variant of SARS CoV2 in Rajasthan

“…Since majority of patients were asymptomatic or had mild disease, it will be difficult to trace and track the positive persons as a result it will spread widely in community (2). In our study we found 23.7 % strains to belonged to BA.2, this lineage doesn’t have the SH69- and Sv70- deletions which lead to S gene drop out or SGTF which has been used a proxy marker for Omicron in Taq Path PCR kits therefore using such kits may not detect Omicron moreover we found a rising trend in BA.2 lineage in our samples hence use of these kits can give false negative for Omicron (7,12). However, a new kit Omisure (TATA Medical and Diagnostics) validated by ICMR for Omicron detection may be used to detect omicron which will be particularly useful to identify if the hospitalised patient is omicron or not as with the increase in positivity all the positives cannot be sequenced anymore (13).…”

“…Though as part of facility quarantine the international travellers and their contacts were initially admitted in designated area of the hospital. As per studies from Gauteng, South Africa only 4.9% case were admitted in hospital in fourth wave which was due to Omicron as compared to 18.9% and 13.7% in third and second waves which were due to Delta and other variants and 28.8% admitted cases in fourth wave had severe disease as compared to 60.1% and 66.9% in third and second waves (7). As per the South African study the proportion of cases admitted in Omicron dominated wave were lower than Delta dominated wave and the sever cases were lower too.…”

Estimating disease severity of Omicron and Delta SARS-CoV-2 infections

“…This seems to point to higher disease severity. However, the in-hospital case fatality ratio of children under 5 in the Omicron wave was 0.5% versus 0.6% in the Delta wave 9 . A similar trend, but with lower case fatality, was seen in older children.…”

“…But is Omicron more severe in children? In children, the fraction of SARS-CoV-2-positive cases admitted to hospital in South Africa doubled during the Omicron wave compared to in the Delta wave 8 , 9 . This seems to point to higher disease severity.…”

Model-based cost-effectiveness analysis of oral antivirals against SARS-CoV-2 in Korea

“…First, the size of the target population or treatment impact may be subject to the future epidemic trend (e.g., influence of new variants) and policy choice (e.g., social distancing policy). For example, the Omicron influence (i.e., transmission appears to be faster, [18,19] but the risk of severity is less when compared to other variants [20][21][22]) may reduce the cost-effectiveness of the treatment as it is likely to increase the size of target population and treatment costs but reduce severity/admission rate and, thus, admission demand.…”