COVID-19 Hospitalization 23 Times Higher for Unvaccinated During Omicron Surge

The COVID-19 Omicron variant may cause milder disease than the Delta variant, but its rapid spread in Los Angeles County still singled out unvaccinated Angelinos.

Until the emergence of the Omicron variant in November 2021, ~100% of the SARS-CoV-2 infections in Los Angeles County (LAC) were caused by the Delta strain, according to a study published this week in MMWR.

The earliest known appearnce of Omicron was in the last week of November and by the week ending December 11th, Delta prevalance had decreased 95%. During the week ending Decmber 18th, Omicron became the dominant variant and accounted for more than half (57%) of all sequenced specimens. As of January 8, Omicron accounted for 99% of sequenced specimens.

Danza et al, writing in MMWR, say that while Omicron disease severity appears lower vs Delta, the rapid rise in infections as it became ascendent drove up hospitalizations and not suprisingly, the increase was most pronounced among the unvaccinated, lower among those fully vaccinated, and lowest among those vaccinated and boosted.

Findings from the study which looked at COVID-19 incidence, hospitalization, and mortality between November 7, 2021 and January 8, 2022 are summarized below and support the continued public health campaign to increase both initial COVID-19 vaccination series and booster doses.


Source: Danza P, Koo TH, Haddix M, et al. SARS-CoV-2 infection and hospitalization among adults aged ≥18 years, by vaccination status, before and during SARS-CoV-2 B.1.1.529 (Omicron) variant predominance — Los Angeles County, California, November 7, 2021–January 8, 2022. MMWR Weekly. 2022;71;177–181.