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Disclosures: The authors report no relevant financial disclosures.
February 01, 2022
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Hospitalization rate 23 times higher for unvaccinated vs. boosted during omicron

Disclosures: The authors report no relevant financial disclosures.
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Data from Los Angeles County during the omicron surge showed that the COVID-19 hospitalization rate was 23 times higher among people who were unvaccinated compared with people who had received a COVID-19 vaccine series and booster.

Moreover, the COVID-19 incidence rate was 3.6 times higher among the unvaccinated compared with people who were boosted, Phoebe Danza, MPH, supervising epidemiologist at the Los Angeles County Department of Public Health, and colleagues reported in MMWR.

Source: Adobe Stock.
Source: Adobe Stock.

According to the report, the earliest known COVID-19 case from the omicron variant of SARS-CoV-2 was identified in Los Angeles County in the final week of November 2021. For their study, Danza and colleagues assessed COVID-19 incidence, hospitalization and mortality rates from Nov. 7, 2021, through Jan. 8, 2022.

Out of 422,966 COVID-19 cases among those aged 18 years and older, 33.6% occurred in unvaccinated people, 13.3% in people who were vaccinated with a booster dose, and 53.2% in those who were vaccinated but did not receive a booster dose.

Unvaccinated people had higher rates of hospitalization (2.8%), ICU admission (0.5%) and mechanical ventilation (0.2%) compared with vaccinated people with a booster (0.7%, 0.08% and 0.03%, respectively), the authors reported.

Deaths were also most common among the unvaccinated (0.3%) compared with those vaccinated with a booster (0.07%) and those vaccinated without a booster (0.08%).

During the week of Dec. 11, the final week the delta variant was the dominant strain of SARS-CoV-2 in the U.S., age-adjusted 14-day cumulative incidence (443.9 per 100,000 people) and hospitalization rates (45.9 per 100,000) were highest among those who were unvaccinated. Incidence (36.1 per 100,00) and hospitalization (0.6 per 100,00) were lowest in people who had received a booster dose.

As of Jan. 8, in the midst of the omicron surge, incidence (6,743.5 per 100,000) and hospitalization (187.8 per 100,000) rates remained highest in those who were unvaccinated. Again, incidence (1,889 per 100,000) and hospitalization (8.2 per 100,000) remained lowest in those who were fully vaccinated with a booster dose.

“Although disease severity appears to be lower for omicron, a rapid increase in infections during omicron predominance has resulted in a relatively substantial volume of hospitalizations,” the authors wrote.