Omicron linked to increase in COVID-19 cases, lower disease severity

(HealthDay)—COVID-19 cases have increased with the emergence of the Omicron variant, but disease severity seems not to have increased, according to research published in the Jan. 25 early-release issue of the U.S. Centers for Disease Control and Prevention Morbidity and Mortality Weekly Report.

A. Danielle Iuliano, Ph.D., from the CDC COVID-19 Emergency Response Team, and colleagues examined data from three surveillance systems and a large health care database to understand the severity of disease and health care utilization associated with the emergence of the Omicron variant in the United States. Multiple indicators were assessed across three high-COVID-19 transmission periods: Dec. 1, 2020, to Feb. 28, 2021 (winter 2020 to 2021); July 15 to Oct. 31, 2021 (delta predominance); and Dec. 19, 2021, to Jan. 15, 2022 (Omicron predominance).

The researchers found that during the Omicron period, the highest daily seven-day moving average to date of cases (798,976 daily cases during Jan. 9 to 15, 2022), emergency department visits (48,238), and admissions (21,586) were reported; compared with previous periods, the highest daily seven-day moving average of deaths was lower during Omicron (1,854 deaths). A maximum of 20.6 percent of staffed inpatient beds were in use for COVID-19 patients during the Omicron period, which was 3.4 and 7.2 percent higher than during the winter 2020 to 2021 and delta periods, respectively; intensive care unit (ICU) bed use did not increase to the same extent. Compared with the previous periods, during the Omicron period, the mean length of stay and percentages admitted to ICU, who received invasive mechanical ventilation, and died in the hospital were lower.

"Although patients hospitalized during the Omicron period have shorter stays and less frequent ICU admissions, the high volume of hospitalizations resulting from high transmission rates during a short period can strain local health care systems in the United States," the authors write.

One author disclosed financial ties to Becton, Dickinson and Company.