Editor's note: The headline of this article was corrected on Jan 31 to state the correct risk reduction for vaccinated residents: 23% to 33%, not 30% to 50%.
A study today in Morbidity and Mortality Weekly Report finds that US nursing home residents who weren't up to date on recommended COVID-19 vaccines were at a 30% to 50% higher risk for infection than those who were current—or a 23% to 33% lower risk for vaccinated residents.
From Oct 10, 2022, to Jan 8, 2023, Centers for Disease Control and Prevention (CDC) researchers analyzed data from the CDC's National Healthcare Safety Network (NHSN) on weekly COVID-19 infections among nursing home residents.
The team compared infection rates among residents who had received the recommended primary monovalent (single-strain) vaccine series and either a monovalent booster dose within the past 2 months or the newer bivalent (two-strain) booster.
Federal mandates require nursing homes certified by the Centers for Medicare & Medicaid Services to report weekly infection and vaccination data to NHSN, the researchers said. Each of the 15,049 facilities reported such data for at least 1 week during the study period, and the vast majority submitted data for all 13 weeks.
Under 50% received a booster
Up-to-date vaccination status was low throughout the study period, rising from 37.5% the week of Oct 23 to 48.9% by study end. Weekly COVID-19 infection rates among unboosted residents were higher than those among booster recipients (range, 9.5 to 18.8 per 1,000 residents vs 7.2 to 15.6), with incidence rate ratios (IRRs) indicating that unboosted residents were at higher risk than their boosted peers (range, 1.3 to 1.5).
This study supports other recent findings that the bivalent booster dose offers additional protection.
"The proportion of nursing home residents in this study who were up to date (48.9%) was lower than the percentage of nursing home residents who completed a primary series (86.1%) and who received monovalent booster doses (87.0%)," the researchers wrote.
The authors noted that nursing home residents are at high risk for COVID-19 infection and poor outcomes, including death because they typically are older, have more chronic conditions, and live in a congregate-care setting.
"This study supports other recent findings that the bivalent booster dose offers additional protection in persons who previously received monovalent vaccines," they wrote.