Trends in Disease Severity and Health Care Utilization During the Early Omicron Variant Period Compared with Previous SARS-CoV-2 High Transmission Periods — United States, December 2020–January 2022
MMWR. Morbidity and Mortality Weekly Report·
- DOI
- 10.15585/mmwr.mm7104e4
- PMID
- 35085225
- PMCID
- PMC9351529
- OpenAlex
- W4207020509
- Study type
- Journal article
- Publisher
- Centers for Disease Control MMWR Office
- Article type
- journal-article
- Integrity
- current
Why this research matters now
Despite lower disease severity during the Omicron period, the high volume of emergency department visits and hospitalizations strained local health care systems, and daily deaths remained substantial. The findings underscore the importance of national emergency preparedness, hospital surge capacity, adequate staffing, staying up to date on vaccination, and following prevention strategies.
Structured evidence summary
Research question
The study examined disease severity and health care utilization during the early Omicron variant period compared with two previous high-transmission periods in the United States.
Study design
CDC analyzed data from three surveillance systems and a large health care database across three high-transmission periods: winter 2020-21, Delta predominance (July-October 2021), and Omicron predominance (December 2021-January 2022). The analysis assessed multiple indicators including cases, emergency department visits, hospitalizations, ICU use, and deaths.
Population and setting
The study covered the United States population during three distinct COVID-19 high-transmission periods. Hospitalized patient data came from 199 U.S. hospitals.
Main findings
The Omicron period recorded the highest daily cases, emergency department visits, and hospital admissions to date, but lower daily deaths than previous periods. Event-to-case ratios for emergency department visits, hospital admissions, and deaths were lower during Omicron than winter 2020-21 and Delta periods. Among hospitalized patients, mean length of stay, ICU admission rates, invasive mechanical ventilation use, and in-hospital deaths were lower during the Omicron period compared with previous periods.
Public-health relevance
Despite lower disease severity during the Omicron period, the high volume of emergency department visits and hospitalizations strained local health care systems, and daily deaths remained substantial. The findings underscore the importance of national emergency preparedness, hospital surge capacity, adequate staffing, staying up to date on vaccination, and following prevention strategies.
Important limitations
This summary is limited to the supplied single-article abstract and metadata and requires the original paper for decision-grade interpretation.
GIDS interpretation
The article is discoverable through GIDS classifier links for SARS, COVID-19, United States, surveillance, transmission dynamics, and vaccination. It provides context on variant-specific severity patterns during a defined epidemiological period in the United States.
Related GIDS surveillance
Literature context does not validate, explain, or change a surveillance signal. Exact and contextual relationships are shown separately.
Evidence relationships
This article has 14 auditable classifier relationships to diseases, places, topics, and study design.