Infections, Hospitalizations, and Deaths Among US Nursing Home Residents With vs Without a SARS-CoV-2 Vaccine Booster

Abstract

ImportanceA SARS-CoV-2 vaccine booster dose has been recommended for all nursing home residents. However, data on the effectiveness of an mRNA vaccine booster in preventing infection, hospitalization, and death in this vulnerable population are lacking.ObjectiveTo evaluate the association between receipt of a SARS-CoV-2 mRNA vaccine booster and prevention of infection, hospitalization, or death among nursing home residents.Design, Setting, and ParticipantsThis cohort study emulated sequentially nested target trials for vaccination using data from 2 large multistate US nursing home systems: Genesis HealthCare, a community nursing home operator (system 1) and Veterans Health Administration community living centers (VHA CLCs; system 2). The cohort included long-term (≥100 days) nursing home residents (10 949 residents from 202 community nursing homes and 4321 residents from 128 VHA CLCs) who completed a 2-dose series of an mRNA vaccine (either BNT162b2 [Pfizer-BioNTech] or mRNA-1273 [Moderna]) and were eligible for a booster dose between September 22 and November 30, 2021. Residents were followed up until March 8, 2022.ExposuresReceipt of a third mRNA vaccine dose, defined as a booster dose (boosted group), or nonreceipt of a booster dose (unboosted group) on an eligible target trial date. If participants in the unboosted group received a booster dose on a later target trial date, they were included in the booster group for that target trial; thus, participants could be included in both the boosted and unboosted groups.Main Outcomes and MeasuresTest-confirmed SARS-CoV-2 infection, hospitalization, or death was followed up to 12 weeks after booster vaccination. The primary measure of estimated vaccine effectiveness was the ratio of cumulative incidences in the boosted group vs the unboosted group at week 12, adjusted with inverse probability weights for treatment and censoring.ResultsSystem 1 included 202 community nursing homes; among 8332 boosted residents (5325 [63.9%] female; 6685 [80.2%] White) vs 10 886 unboosted residents (6865 [63.1%] female; 8651 [79.5%] White), the median age was 78 (IQR, 68-87) years vs 78 (IQR, 68-86) years. System 2 included 128 VHA CLCs; among 3289 boosted residents (3157 [96.0%] male; 1950 [59.3%] White) vs 4317 unboosted residents (4151 [96.2%] male; 2434 [56.4%] White), the median age was 74 (IQR, 70-80) vs 74 (IQR, 69-80) years. Booster vaccination was associated with reductions in SARS-CoV-2 infections of 37.7% (95% CI, 25.4%-44.2%) in system 1 and 57.7% (95% CI, 43.5%-67.8%) in system 2. For hospitalization, reductions of 74.4% (95% CI, 44.6%-86.2%) in system 1 and 64.1% (95% CI, 41.3%-76.0%) in system 2 were observed. Estimated vaccine effectiveness for death associated with SARS-CoV-2 was 87.9% (95% CI, 75.9%-93.9%) in system 1; however, although a reduction in death was observed in system 2 (46.6%; 95% CI, −34.6% to 94.8%), this reduction was not statistically significant. A total of 45 SARS-CoV-2–associated deaths occurred in system 1 and 18 deaths occurred in system 2. For the combined end point of SARS-CoV-2–associated hospitalization or death, boosted residents in system 1 had an 80.3% (95% CI, 65.7%-88.5%) reduction, and boosted residents in system 2 had a 63.8% (95% CI, 41.4%-76.1%) reduction.Conclusions and RelevanceIn this study, during a period in which both the Delta and Omicron variants were circulating, SARS-CoV-2 booster vaccination was associated with significant reductions in SARS-CoV-2 infections, hospitalizations, and the combined end point of hospitalization or death among residents of 2 US nursing home systems. These findings suggest that administration of vaccine boosters to nursing home residents may have an important role in preventing COVID-19–associated morbidity and mortality.

Durability of immunity and clinical protection in nursing home residents following bivalent SARS-CoV-2 vaccination

“…Too few people died for the estimated 74.4% reduction in death at 16 weeks to reach statistical significance. * With the exception of our follow-up time decisions these results mimic the methodology previously published (15).…”

“…We deployed a Target Trial Emulation (TTE) approach, similar to what we reported for clinical outcomes following monovalent boosters (15,16), to assess additional clinical effectiveness following the introduction of a bivalent SARS-CoV-2 vaccine in September 2022. On each day from September 18 on we evaluated if Veterans living in a Veterans Administration-managed nursing home, i.e., Community Living Center or CLC, were eligible for inclusion.…”

Second monovalent SARS-CoV-2 mRNA booster restores Omicron-specific neutralizing activity in both nursing home residents and health care workers

“…To date, more than 1.3 million NH residents in the US have been infected with SARS-CoV-2 and over 160,000 have died [4] . Vaccination is the best intervention to reduce both mortality and morbidity in NH residents [5] , [6] , [7] . However, in the setting of new SARS-CoV-2 variants, there is still some uncertainty as to the optimal timing and frequency of consecutive booster vaccinations in this frail population.…”

Absolute and Relative Vaccine Effectiveness of Primary and Booster Series of COVID-19 Vaccines (mRNA and Adenovirus Vector) Against COVID-19 Hospitalizations in the United States, December 2021–April 2022

“…This result was similar to the current study and more typical of studies covering the Omicron-predominant period. Higher rVE reported in several studies [ 7 , 8 , 10 , 22 ] could also be associated with larger reductions in risk that might be more common in older populations [ 7 , 10 , 22 , 23 ] or could be associated with smaller reductions in risk typical of studies in locales with near-universal vaccination or during earlier variant-predominant periods (eg, Alpha, Delta) with generally higher aVE for the primary series alone [ 8 , 24 ]. Two studies that demonstrate large changes in rVE observed based on time elapsed after a 1st booster dose (12%–85% during 7–65 days after a first booster dose in one study [ 11 ], 27%–64% during 7–69 days after a second booster dose in another study [ 25 ]) show that follow-up period can also substantially influence rVE metrics.…”