SARS-CoV-2 waves in over 1,30,000 Covid-19 patients. They found that although the unadjusted rates of hospital admission and mortality appeared to be higher in previous waves compared to the Omicron period, the risks of hospitalisation and mortality were nearly identical. "After adjusting for confounders … we found that the risks of hospitalisation and mortality were nearly identical between periods.
Our analysis suggests that the intrinsic severity of the Omicron variant may be as severe as previous variants," the authors of the study noted.
The B.1.1.529 (Omicron) variant has previously been reported as more transmissible, but less severe than other SARS-CoV-2 variants.
The researchers, however, said that understanding the intrinsic severity of Omicron is challenging. "A number of confounding factors affecting severity in Covid-19 have changed since the start of the pandemic and may continue to change," the authors of the study said. "Any comparison between SARS-CoV-2 variants without adequately adjusting and controlling for important confounders that may change over time such as vaccination status and healthcare utilisation, can mislead both the public and medical experts of the true danger of the variant," they added.