How serious is Omicron compared to Delta?

Severe Acute Respiratory Syndrome Limited data on comparison of disease severity in adult inpatients with coronavirus disease 2019 (COVID-19) caused by an omicron or delta variant of coronavirus 2 (SARS-CoV-2) I am.New survey published on preprint server medRxiv * Three different health outcomes were used to assess the severity of the disease in adult patients hospitalized with COVID-19.

study: Severity of Omicron (B.1.1.529) and Delta (B.1.1.617.2) SARS-Cov-2 infections in hospitalized adults: prospective cohort study.. Image Credit: Gorodenkoff / Shutterstock.com

Preface

A variant of the SARS-CoV-2 delta emerged in March 2021 and subsequently triggered a new wave of catastrophic COVID-19 cases worldwide. In the United Kingdom, cases of COVID-19 increased rapidly, first as a result of the delta variant and then as a result of the omicron variant after November 2021. In fact, the SARS-CoV-2 Omicron variant caused 95% of all UK cases by the end of December 2021.

In the current study, researchers at the University of Bristol and Pfizer investigated the severity of the disease, considering that the hospitalization rate during the Omicron wave was much lower than in the previous wave. In particular, the current study was conducted after the COVID-19 vaccine proved to be effective in preventing hospitalization for Omicron infection.Therefore, the reduced severity of Omicron may be due to the low pathogenicity of the mutant or the widespread application of the vaccine throughout the UK.

Scientists used three severity measures to ensure that the analysis was unbiased due to widespread vaccination, the presence of underlying disease, frailty, age, and pathogenicity. These measurements include the Pulmonary Function Index (FiO)₂) Over 28%, World Health Organization (WHO) result score over 5, hospitalization period (LOS) over 3 days after admission. These measurements were evaluated for both Omicron and Delta patients, supplementing age, frailty, and vaccination status.

Survey results

Omicron inpatients were found to be 71 years older than Delta inpatients, 58 years. In addition, adult inpatients diagnosed with the SARS-CoV-2 Omicron variant were more likely to receive a third booster than Delta inpatients and had an underlying disorder. Omicron’s hospitalization rate increased over time and eventually exceeded the delta rate by the end of December 2021.

In late December 2021, when Omicron’s hospitalization increased, the median age shifted from younger to older. Despite being older and frail, the outcomes of these patients were less severe than those diagnosed with the delta variant, except for those aged 85 years and older. Similarly, LOS decreased with Omicron, except for those over 70 years of age.

A detailed breakdown of the three selected indicators of hospitalization severity stratified by the SARS-CoV-2 variant, and three binary indicators of hospital burden for inpatients and the SARS-CoV-2 variant and patient age. Comparison of relationships with hospitals.

Omicron-related hospitalizations were approximately 60%, 70%, and 20% less likely to require high-flow oxygen, positive pressure ventilation support, or more important care, respectively. The chances of LOS exceeding 3 days were 20% lower for Omicron.

This association between Omicron and less severe illness was observed in both vaccinated and unvaccinated patients. Nonetheless, vaccinated patients showed that their high-flow oxygen requirements were more than 20% lower and the need for more advanced interventions was further reduced by nearly 40%.

Distribution of (A) patients requiring different peak levels of oxygen supplementation, (B) different ventilation requirements as defined by WHO results or clinical progression scores, and (C) different lengths of stay. (D) Percentage of patients requiring high flow oxygen above 28% FiO₂, (E) WHO result score> 5 (NIPPV required), and (F) Hospitalization length is more than 3 days when evaluated on the 7th day after admission. The error bars show 95% of the binomial confidence intervals for each result compared to the other results. FiO₂Inspired oxygen concentration; LOS, duration of stay; NIPPV, non-invasive positive pressure ventilation

Implications

The findings indicate that the SARS-CoV-2 Omicron variant is associated with less severe infections compared to the Delta variant, thus supporting previous reports.

Researchers predict that their findings may contribute to the evaluation of future hospital care and service plans. For example, total mechanical and non-invasive ventilation and oxygen capacity can be planned using these and similar reports.

Nevertheless, the Omicron subspecies is clearly more contagious than any other SARS-CoV-2 subspecies to date. As a result, the SARS-CoV-2 omicron mutant causes much higher infections. This means that even a much lower rate of hospitalization can have a significant impact on the healthcare system.

One in five Omicron patients require oxygen supplementation, 6% require positive pressure ventilation, and 4% die of infection. Therefore, a very high infection rate with this variant can inevitably overwhelm the hospital. The risk of infection of hospitals and other medical staff and the subsequent need for quarantine also increases the likelihood of staff shortages during the Omicron-related surge.

Decreased oxygen requirements and lower WHO outcome scores may result in a larger wave of community Omicron infections with depleted oxygen supply and more dependent care beds than in Delta and other previous variants. It suggests that it is low.Vaccination is expected to further reduce these risks.. “

*Important Notices

medRxiv Publish preliminary scientific reports that should not be considered definitive as they have not been peer-reviewed, guide clinical practice / health-related behaviors, and should not be treated as established information.