Closeup of clinician's hands getting vaccine dose ready

An additional dose of a COVID-19 vaccine provided better protection against the omicron variant than an initial vaccine series alone, according to a new analysis of data from residents in more than 14,000 U.S. skilled nursing facilities.

The booster dose had 47% relative efficacy against infection with the variant, the Centers for Disease Control and Prevention reported Thursday. The agency’s investigators examined surveillance and vaccination coverage data for SNF residents from the CDC’s National Healthcare Safety Network between February and March, 2022. That’s when the omicron variant accounted for more than 99% of sequenced cases.

“Efforts to keep nursing home residents up-to-date with vaccination should be implemented in conjunction with other COVID-19 prevention strategies,” concluded Namrata Prasad, Ph.D., and colleagues. This includes testing and vaccination of nursing home staff members and visitors, they wrote in the CDC’s Morbidity and Mortality Weekly report.

Same risk for severe illness

In the meantime, new findings have contradicted the conclusion that omicron infections generally lead to less severe outcomes when compared with previous SARS-CoV-2 variants. Preliminary results from a study comparing 13,000 COVID-19 patient outcomes in Massachusetts over the last two years show nearly identical hospitalization and mortality during the omicron period and previous variant waves. The study is currently undergoing peer review.

Additional data from the CDC also shows that the SARS-CoV-2 virus continues to mutate and spread. Another new omicron subvariant is likely to become dominant within weeks, the agency reported.

In this latest CDC analysis, for the week ending Saturday, the new BA.2.12.1 variant accounted for about 36% of new cases in the United States, up 26% from the prior week, according to the New York Times. It is unknown what risks it poses when compared to the most recent omicron variant, BA.2, the news outlet reported.

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