Updated study shows Omicron appears to be less severe than Delta

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A recent study done by Public Health Ontario suggests that the Omicron variant of COVID-19 is less severe than the Delta variant so far.

Public Health Ontario said the study of over 11,000 Omicron cases in Ontario showed that the risk of hospitalization or death was 65 per cent lower when compared to closely matched Delta cases. A previous examination of the data from between November 22 and December 17 showed the risk of hospitaliaztion or death was 54 per cent lower.

The agency warns the estimates are preliminary because the study was done at the end of December 2021 based on case and contact information between November 22, 2021 and December 25, 2021. The dates were chosen based on the likelihood of a case being Omicron given the rising prevalence in the province.

Omicron has been deemed more transmissible than other strains of COVID-19, but it was less clear how severe it was.

Of the 11,622 cases of Omicron included in the study, there were three deaths (0.03 per cent), 59 hospitalizations (0.5 per cent), and seven admissions to intensive care (0.06 percent). For Delta, the rates were 0.12 per cent for death, 1.6 per cent for hospitalization, and 0.42 per cent for intensive care.

“This study has some limitations, in particular the short follow-up duration and potential misclassification due to incidental findings from hospital admissions screening, or incomplete public health follow-up as incidence increased,” Public Health Ontario said. “However, Omicron appears to be the first dominant variant to demonstrate a decline in disease severity. While severity may be reduced, due to the transmissibility of Omicron, the absolute number of hospitalizations and impact on the healthcare system is likely to be significant.”

The agency said the results align with findings from South Africa, Scotland, and England, which have all demonstrated substantial decreases in risk of hospitalization associated with Omicron. The World Health Organization designated Omicron as a variant of concern on November 26, 2021.

More information can be found here.