Nursing home residents who are up to date with their COVID-19 vaccines are 30% to 50% less likely to become infected with SARS-CoV-2 than their fellow residents who haven’t gotten boosted, a new federal study finds.

The data is based on weekly incidence rates in federally supported nursing homes between Oct. 10, 2022 and Jan. 8, 2023. The analysis provides a much-needed estimate of how well the bivalent booster shot works to keep residents safe, wrote the authors of an article published Friday in the Centers for Disease Control and Prevention’s Morbidity and Mortality Weekly Report.

The official definition of “up to date” has changed throughout the pandemic. It now includes an initial series of shots with the original COVID-19 vaccines, followed by the receipt of an updated, bivalent booster shot. Two bivalent shots were authorized in August 2022, and individuals are currently eligible to get one if they’ve had their last COVID-19 vaccination two or more months ago.

Half of residents ‘up to date’

During the study period, up-to-date vaccination status was only 49% among residents nationally. At the same time, weekly COVID-19 incidence rates remained consistently higher in residents who had not received the bivalent booster shot when compared to their boosted peers. 

The two bivalent vaccines, made by Pfizer-BioNTech and Moderna, include protection against forms of the omicron variant. A recent federal study found that they provide 73% additional protection against hospitalization when compared with the original monovalent shots that are now used as primary vaccinations.

Tackling barriers

“It is critical that nursing home residents stay up to date with COVID-19 vaccines and receive a bivalent booster dose to maximize protection against COVID-19,” wrote Jeneita M. Bell, MD, of the CDC’s National Center for Emerging and Zoonotic Infectious Diseases, in the new study.

Bell and colleagues recommended that efforts be made to address the barriers to increasing bivalent COVID-19 booster dose coverage in this population to prevent illness, severe disease and death.

Future of monovalent shots

In related news, federal vaccine advisers last week recommended that the bivalent shot serve as both an initial series and a booster, effectively replacing the older, monovalent shots. It is now up to the Food and Drug Administration to decide whether and how to put that recommendation into practice.

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