Feb. 1 (UPI) — Unvaccinated adults were 23 times more likely to be hospitalized with the COVID-19 Omicron variant than those who were fully vaccinated and had received a booster shot, according to data released Tuesday by the Centers for Disease Control and Prevention.
They also were four times more likely to get infected with the virus, the data showed.
These figures are lower than they were for the Delta variant, which was the predominant one in circulation between last spring and mid-December, the CDC said.
With Delta, the unvaccinated were 12 times more likely to get infected and 83 times more likely to be hospitalized with the virus than those who were fully vaccinated and boostered, according to the agency.
“These findings align with those from recent studies, indicating that COVID-19 vaccination protects against severe COVID-19 caused by [virus] variants, including Omicron,” the CDC researchers wrote.
“Being up to date with COVID-19 vaccination is critical to protecting against [COVID-19] infection and hospitalization,” they said.
The findings are based on an analysis of infections in Los Angeles County, Calif. between Nov. 7 and Jan. 8, according to the CDC.
That period roughly coincides with the end of the surge in cases caused by the virus’ Delta variant and the new one caused by Omicron, which first emerged in South Africa in late November.
Of the more than 422,000 cases in the region during that two-month period, about 142,000, or 34%, occurred in unvaccinated people, the data showed.
Among these cases, about 4,000, or 3%, were hospitalized due to the virus, the CDC said.
Just over 56,000 of the cases involved people who were fully vaccinated and had received a booster dose, and less than 1% of them resulted in hospitalization, according to the agency.
About 225,000, or 53%, of the cases were in people who were fully vaccinated but had not yet been boostered, and 2,300, or 1%, of them were hospitalized with the virus, the data showed.
With the Delta variant, the unvaccinated were four times more likely to be infected and 13 times more likely to be hospitalized with the virus than those who were fully vaccinated but not yet boostered, according to the CDC.
Although Omicron is believed to cause less severe illness compared to the Delta variant, the United States still saw a surge in hospitalizations as the strain spread, likely because it is more contagious than earlier ones.
During analysis period “infections increased rapidly among … adults with the largest increase occurring as Omicron displaced Delta as the predominant circulating variant,” the CDC researchers wrote.
“Whereas incidence and hospitalization rates were higher during the Omicron-predominant weeks compared with those during Delta predominance, rate ratios indicated continued protection conferred by vaccine against severe disease,” they said.
