Omicron Hospitalizations Up to 23 Times Higher for the Unvaccinated

During the Omicron wave, unvaccinated adults were 23 times more likely to be hospitalized, and nearly four times as likely to be infected as vaccinated adults who had also received a booster, according to data from Los Angeles County.

And compared to fully vaccinated but non-boosted adults, unvaccinated individuals were more than five times more likely to be hospitalized, and about twice as likely to be infected during this time, reported Sharon Balter, MD, of the Los Angeles County Department of Public Health, and colleagues.

Moreover, unvaccinated adults were significantly more likely to require ICU admission, intubation for mechanical ventilation, or die compared to vaccinated adults with or without a booster, they stated in an early edition of the Morbidity and Mortality Weekly Report.

They examined data from COVID surveillance and the California Immunization Registry 2 from Nov. 7, 2021 to Jan. 8, 2022 by both vaccination status and variant predominance. Dec. 11, 2021 was the last week of Delta predominance in the area.

There were 422,966 COVID infections throughout the entire time period, 53% among vaccinated/non-boosted adults, 34% among unvaccinated adults, and 13% among fully vaccinated/boosted adults.

Overall, unvaccinated adults were more likely to be hospitalized (2.8%), admitted to an ICU (0.5%), and require mechanical ventilation (0.2%). Rates were far lower in fully vaccinated persons without a booster (1.0%, 0.12%, and 0.05%, respectively) and with a booster (0.7%, 0.08%, and 0.03%).

And 0.3% of unvaccinated adults died versus less than 0.1% of vaccinated and vaccinated/boosted adults.

During the Delta period, unvaccinated adults were 83 times more likely to be hospitalized and 12 times more likely to be infected than vaccinated/boosted adults, and almost 13 times more likely to be hospitalized and 4 times more likely to be infected versus vaccinated but not boosted adults.

Balter and colleagues concluded that their research shows the importance of being up to date on COVID vaccination, noting that, “these findings align with those from recent studies, indicating that COVID-19 vaccination protects against severe COVID-19 caused by SARS-CoV-2 variants, including Omicron.”

CDC recommends that all adults receive a booster dose of vaccine at least 5 months after their initial Pfizer or Moderna two-dose primary series.