The findings by Southern California researchers of the Kaiser Group published as a preprint in MedRxiv posted 11th January 2022 highlight this.
Their results showed a near tenfold reduction in deaths with the Omnicom variant.
The Omicron variant of SARS-CoV-2 has rapidly achieved global dissemination, accounting for most infections in the United States by December 2021.
However, the risk of severe outcomes associated with Omicron infections, as compared to earlier SARS-CoV-2 variants remains unclear.
This study analysed clinical and epidemiological data from cases testing positive for SARS-CoV-2 infection within the Kaiser Permanente Southern California Healthcare system from November 30th 2021 to January 1st 2022.
Their analysis included 52,297 cases with Omicron and 168,982 cases with Delta infections respectively.
Hospital admissions occurred among 235, 0.5% and 222, 1.3% of cases with Omicron and Delta respectively.
Amongst cases first tested in outpatient settings, adjusted hazard ratios for any subsequent hospital admissions and symptomatic hospital admissions associated with Omicron variant infection were 0.48 and 0.47 respectively.
Rates for ICU admission and mortality after an outpatient positive test were 0.26 and 0.09 fold higher among cases of the Omicron variant infection as compared to cases of Delta variant infection.
Zero cases with Omicron variant infection received mechanical ventilation, as compared to 11 cases with Delta variant infections throughout the period of follow-up.
Median duration of hospital stay was 3.4 days shorter for hospitalised cases with Omicron variant infections as compared with hospitalised patients with Delta variant infections, reflecting a 69.6% reduction in hospital length of stay.
These findings therefore showed a near tenfold reduction in deaths with the Omicron variant.
However, the findings were not definitive as to determine whether Omicron was intrinsically less severe than Delta or vaccinations and prior infections had played a role and may differ during the time periods studied.
The LGP commends the Government on its vaccination programme.
Dr Paul Ettlinger
BM, DRCOG, FRCGP, FRIPH, DOccMed