Severity of COVID-19 among Residents in Aged Care Facilities in Victoria, Australia: A Retrospective Cohort Study Comparing the Delta and Omicron Epidemic Periods.
Michael Muleme, Bridgette J McNamara, Frances H Ampt and 14 others
PMID 36806486WHAT IT FOUND
During Omicron, aged-care residents had lower hospitalization and death per case than during Delta, but more cases and deaths overall.
Nurses should not assume mild disease: monitor residents, maintain infection control, and consider vaccination timing.
Key findings
01Hospitalization risk was lower during the Omicron period than during the Delta period: 8.2% versus 24.6%.
02Case fatality risk was lower during the Omicron period than during the Delta period: 11.4% versus 18.7%.
03The Omicron period had more resident cases and deaths overall than the Delta period: 1882 versus 994 cases, and 214 versus 186 deaths.
STILL TO COME
How it was doneWhat they foundWhat it means for RNs
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What it does not show
The Omicron period analysed was much shorter than the Delta period, and early Omicron case reporting relied on rapid antigen tests and a new definition, so some cases may have been missed. Data on comorbidities and frailty were not available, so residents in the two periods may not have been equally vulnerable. The definition of vaccine protection differed between periods: at least 2 doses for Delta and at least 3 doses for Omicron. Some hospitalizations were for outbreak management rather than clinical need, which can make hospitalization risk hard to interpret. This is an observational comparison of epidemic periods, not a controlled trial, so it cannot prove that the variant alone caused the lower severity. Results are from Victorian residential aged care facilities and may not apply to all aged care populations.
The easy way to misread this
Do not read the lower hospitalization and death percentages as proof that Omicron is mild in aged care. The Omicron period had more resident cases and deaths overall, and some hospital transfers were for outbreak management rather than clinical need.