Fast magnetization transfer saturation imaging of the brain using MP2RAGE T1 mapping.

PURPOSE: Magnetization transfer saturation (MTsat) mapping is commonly used to examine the macromolecular content of brain tissue. This study compared variable flip angle (VFA) T1 mapping against compressed-sensing MP2RAGE (csMP2RAGE) T1 mapping for accelerating MTsat imaging. METHODS: VFA, MP2RAGE, and csMP2RAGE were compared against inversion-recovery T1 in an aqueous phantom at 3 T. The same 1-mm VFA, MP2RAGE, and csMP2RAGE protocols were acquired in 4 healthy subjects to compare T1 and MTsat. Bloch-McConnell simulations were used to investigate differences between the phantom and in vivo T1 results. Ten healthy controls were imaged twice with the csMP2RAGE MTsat protocol to quantify repeatability. RESULTS: The MP2RAGE and csMP2RAGE protocols were 13.7% and 32.4% faster than the VFA protocol, respectively. At these scan times, all approaches provided strong repeatability and accurate T1 times (< 5% difference) in the phantom, but T1 accuracy was more impacted by T2 for VFA than for MP2RAGE. In vivo, VFA estimated longer T1 times than MP2RAGE and csMP2RAGE. Simulations suggest that the differences in the T1 measured using VFA, MP2RAGE, and inversion recovery could be explained by the magnetization-transfer effects. In the test-retest experiment, we found that the csMP2RAGE has a minimum detectable change of 2.3% for T1 mapping and 7.8% for MTsat imaging. CONCLUSIONS: We demonstrated that MP2RAGE can be used in place of VFA T1 mapping in an MTsat protocol. Furthermore, a shorter scan time and high repeatability can be achieved using the csMP2RAGE sequence.

Bacteriophage therapy and current delivery strategies for orthopedic infections: A SCOPING review.

OBJECTIVES: Interest in phages as adjunctive therapy to treat difficult infections has grown in the last decade. However, phage dosing and delivery for orthopedic infections have not been systematically summarized. METHODS: Following PRISMA-ScR guidelines, we conducted a SCOPING review through September 1st, 2023, of MEDLINE, Embase, Web of Science Core Collection, and Cochrane Central. RESULTS: In total, 77 studies were included, of which 19 (24.7%) were in vitro studies, 17 (22.1%) were animal studies, and 41 (53.2%) were studies in humans. A total of 137 contemporary patients receiving phage therapy are described. CONCLUSIONS: Direct phage delivery remains the most studied form of phage therapy, notably in prosthetic joint infections, osteomyelitis, and diabetic foot ulcers. Available evidence describing phage therapy in humans suggests favorable outcomes for orthopedic infections, though this evidence is composed largely of low-level descriptive studies. Several phage delivery devices have been described, though a lack of comparative and in-human evidence limits their therapeutic application. Limitations to the use of phage therapy for orthopedic infections that need to be overcome include a lack of understanding related to optimal dosing and phage pharmacokinetics, bacterial heterogeneity in an infection episode, and phage therapy toxicity.

Controlling Reactivity and Selectivity in the Mizoroki-Heck Reaction: High Throughput Evaluation of 1,5-Diaza-3,7-diphosphacyclooctane Ligands.

We report a high throughput evaluation of the Mizoroki-Heck reaction of diverse olefin coupling partners. Comparison of different ligands revealed the 1,5-diaza-3,7-diphosphacyclooctane (P2N2) scaffold to be more broadly applicable than common "gold standard" ligands, demonstrating that this family of readily accessible diphosphines has unrecognized potential in organic synthesis. In particular, two structurally related P2N2 ligands were identified to enable the regiodivergent arylation of styrenes. By simply altering the phosphorus substituent from a phenyl to tert-butyl group, both the linear and branched Mizoroki-Heck products can be obtained in high regioisomeric ratios. Experimental and computational mechanistic studies were performed to further probe the origin of selectivity, which suggests that both ligands coordinate to the metal in a similar manner but that rigid positioning of the phosphorus substituent forces contact with the incoming olefin in a π-π interaction (for P-Ph ligands) or with steric clash (for P-tBu ligands), dictating the regiocontrol.

Optimization of acquisition parameters for cortical inhomogeneous magnetization transfer (ihMT) imaging using a rapid gradient echo readout.

PURPOSE: Imaging biomarkers with increased myelin specificity are needed to better understand the complex progression of neurological disorders. Inhomogeneous magnetization transfer (ihMT) imaging is an emergent technique that has a high degree of specificity for myelin content but suffers from low signal to-noise ratio (SNR). This study used simulations to determine optimal sequence parameters for ihMT imaging for use in high-resolution cortical mapping. METHODS: MT-weighted cortical image intensity and ihMT SNR were simulated using modified Bloch equations for a range of sequence parameters. The acquisition time was limited to 4.5 min/volume. A custom MT-weighted RAGE sequence with center-out k-space encoding was used to enhance SNR at 3 T. Pulsed MT imaging was studied over a range of saturation parameters, and the impact of the turbo factor on the effective ihMT resolution was investigated. 1 mm isotropic ihMTsat maps were generated in 25 healthy adults. RESULTS: Greater SNR was observed for larger number of bursts consisting of 6-8 saturation pulses each, combined with a high readout turbo factor. However, that protocol suffered from a point spread function that was more than twice the nominal resolution. For high-resolution cortical imaging, we selected a protocol with a higher effective resolution at the cost of a lower SNR. We present the first group-average ihMTsat whole-brain map at 1 mm isotropic resolution. CONCLUSION: This study presents the impact of saturation and excitation parameters on ihMTsat SNR and resolution. We demonstrate the feasibility of high-resolution cortical myelin imaging using ihMTsat in less than 20 min.

A kinetic study of thiol addition to N-phenylchloroacetamide.

Irreversible enzyme inhibitors bind covalently to their target and permanently limit its function. The redox-sensitive thiol group on the side chain of cysteine (Cys) residues is often the nucleophilic group that is targeted for reaction with the electrophilic warhead of irreversible inhibitors. While the acrylamide group is the warhead applied most frequently currently in the design of inhibitors with therapeutic potential, the chloroacetamide group offers a comparable reactivity profile. In that context, we have studied the details of the mechanism of thiol addition to N-phenylchloroacetamide (NPC). A kinetic assay was developed to accurately monitor the reaction progress between NPC and a small library of thiols with varying pKa values. From these data, a Brønsted-type plot was constructed, from which a ßnucRS- value of 0.22 ± 0.07 was derived, indicative of a relatively early transition state with respect to attack by the thiolate. The halide leaving group was also varied, for the reaction with one thiol, providing rate constants consistent with a transition state that is early with respect to leaving group departure. The effects of temperature and ionic strength were also studied, and all data are consistent with an early transition state for a concerted SN2 mechanism of addition. Molecular modelling was also performed, and these calculations confirm the concerted transition state and relative reactivity of the haloacetamides. Finally, this study allows a detailed comparison of the reactivity and reaction mechanisms of the chloroacetamide group with the benchmark acrylamides used in many irreversible inhibitor drugs.

Loss of age-related laminar differentiation of intracortical myelin in bipolar disorder.

Age-related changes of intracortical myelin in bipolar disorder (BD) have been observed to deviate from the quadratic age curve observed in healthy controls (HC), but it is unclear if this holds at varying cortical depths. From BD (n = 44; age range = 17.6-45.5 years) and HC (n = 60; age range = 17.1-45.8 years) participants, we collected 3T T1-weighted (T1w) images with strong intracortical contrast. Signal values were sampled from 3 equivolume cortical depths. Linear mixed models were used to compare age-related changes in the T1w signal between depths and between groups at each depth. In HC, the age-related changes were significantly different between the superficial one-fourth depth and the deeper depths in the right ventral somatosensory (t = -4.63; FDRp = 0.00025), left dorsomedial somatosensory (t = -3.16; FDRp = 0.028), left rostral ventral premotor (t = -3.16; FDRp = 0.028), and right ventral inferior parietal cortex (t = -3.29; FDRp = 0.028). BD participants exhibited no differences in the age-related T1w signal between depths. Illness duration was negatively correlated with the T1w signal at the one-fourth depth in the right anterior cingulate cortex (rACC; rho = -0.50; FDRp = 0.029). Physiological age-related and depth-specific variation in the T1w signal were not observed in BD. The T1w signal in the rACC may reflect lifetime disease burden in the disorder.

A mechanistic study of thiol addition to N-acryloylpiperidine.

Nucleophilic cysteine (Cys) residues are present in many enzyme active sites and represent the target of many different irreversible enzyme inhibitors. Given its fine balance between aqueous stability and thiolate reactivity, the acrylamide group is a particularly popular warhead pharmacophore among inhibitors designed for biological and therapeutic application. The acrylamide group is well known to undergo thiol addition, but the precise mechanism of this addition reaction has not been studied in as much detail. In this work we have focussed on the reaction of N-acryloylpiperidine (AcrPip), which represents a motif found in many targeted covalent inhibitor drugs. Using a precise HPLC-based assay, we measured the second order rate constants for the reaction of AcrPip with a panel of thiols possessing different pKa values. This allowed construction of a Brønsted-type plot that reveals the relative insensitivity of the reaction to the nucleophilicity of the thiolate. By studying temperature effects, we were able to construct an Eyring plot from which the enthalpy and entropy of activation were calculated. Ionic strength and solvent kinetic isotope effects were also studied, informing on charge dispersal and proton transfer in the transition state. DFT calculations were also performed, providing information on the potential structure of the activated complex. Taken together, these data strongly support one cohesive addition mechanism that is the microscopic reverse of the E1cb elimination, and highly relevant to the intrinsic thiol selectivity of AcrPip inhibitors and their subsequent design.

A mechanistic study of thiol addition to N-phenylacrylamide.

Cysteine (Cys) residues contain a redox-sensitive thiol and are commonly found in enzyme active sites. In recent years, the presence of a reactive thiolate group on a protein has been exploited in the development of irreversible enzyme inhibitors as therapeutic agents. Many targeted covalent inhibitors (TCIs) are designed to covalently react with a specific Cys residue on a target protein active site, irreversibly modifying the target and inhibiting its normal function. The electrophilic warhead most commonly used in this way is the acrylamide functional group. Although the acrylamide group is well known for its ability to undergo thiol-addition reactions, very few studies have been conducted to elucidate the detailed mechanism of this reaction, which inspired us to conduct a thorough kinetic investigation. First, we developed a robust kinetic assay to accurately monitor reaction progress between N-phenylacrylamide (NPA) and a small library of alkyl thiols having widely varying pKa values. This allowed us to construct a Brønsted-type plot for the thiol addition reaction, revealing a ßnucRS- value of 0.07 ± 0.04. We also studied the solvent kinetic isotope effects (SKIEs), pH dependence, and temperature dependence of the reaction, which showed that reaction has a relatively large negative ΔS‡, and a small ΔH‡. Computational studies provided a structure for the transition state that is consistent with the experimental data. All of these data are consistent with rate-limiting nucleophilic attack, followed by rapid protonation of the enolate, corresponding to the microscopic reverse of the E1revcb elimination mechanism.

Therapeutic high affinity T cell receptor targeting a KRASG12D cancer neoantigen.

Neoantigens derived from somatic mutations are specific to cancer cells and are ideal targets for cancer immunotherapy. KRAS is the most frequently mutated oncogene and drives the pathogenesis of several cancers. Here we show the identification and development of an affinity-enhanced T cell receptor (TCR) that recognizes a peptide derived from the most common KRAS mutant, KRASG12D, presented in the context of HLA-A*11:01. The affinity of the engineered TCR is increased by over one million-fold yet fully able to distinguish KRASG12D over KRASWT. While crystal structures reveal few discernible differences in TCR interactions with KRASWT versus KRASG12D, thermodynamic analysis and molecular dynamics simulations reveal that TCR specificity is driven by differences in indirect electrostatic interactions. The affinity enhanced TCR, fused to a humanized anti-CD3 scFv, enables selective killing of cancer cells expressing KRASG12D. Our work thus reveals a molecular mechanism that drives TCR selectivity and describes a soluble bispecific molecule with therapeutic potential against cancers harboring a common shared neoantigen.

Tecovirimat for the Treatment of Human Monkeypox: An Initial Series From Massachusetts, United States.

A large, ongoing multicountry outbreak of human monkeypox has the potential to cause considerable morbidity and mortality. Therapeutics for the treatment of smallpox, a related Orthopoxvirus, may be used and affect the natural history of monkeypox. We present 3 patients from our hospitals treated with tecovirimat, a pan-Orthopoxvirus inhibitor currently available under an expanded access investigational new drug protocol for monkeypox.

Low-frequency HIV-1 drug resistance mutations in antiretroviral naïve individuals in Botswana.

BACKGROUND: Individuals living with human immunodeficiency virus (HIV) who experience virological failure (VF) after combination antiretroviral therapy (cART) initiation may have had low-frequency drug resistance mutations (DRMs) at cART initiation. There are no data on low-frequency DRMs among cART-naïve HIV-positive individuals in Botswana. METHODS: We evaluated the prevalence of low-frequency DRMs among cART-naïve individuals previously sequenced using Sanger sequencing. The generated pol amplicons were sequenced by next-generation sequencing. RESULTS: We observed low-frequency DRMs (detected at <20% in 33/103 (32%) of the successfully sequenced individuals, of whom four also had mutations detected at >20%. K65R was the most common low-frequency DRM detected in 8 individuals. Eighty-two of the 103 individuals had follow-up viral load data while on cART. Twenty-seven of the 82 individuals harbored low-frequency DRMs. Only 12 of 82 individuals experienced VF. The following low-frequency DRMs were observed in four individuals experiencing VF: K65R, K103N, V108I, and Y188C. No statistically significant difference was observed in the prevalence of low-frequency DRMs between individuals experiencing VF (4/12) and those not experiencing VF (23/70) (P = .97). However, individuals with non-nucleoside reverse transcriptase inhibitors-associated low-frequency DRMs were 2.68 times more likely to experience VF (odds ratio, 2.68; 95% confidential interval, 0.4-13.9) compared with those without (P = .22). CONCLUSION: Next-generation sequencing was able to detect low-frequency DRMs in this cohort in Botswana, but these DRMs did not contribute significantly to VF.

Interaction between Antimicrobial Peptide Magainin 2 and Nonlipid Components in the Bacterial Outer Envelope.

Antimicrobial peptides (AMPs) offer advantages over conventional antibiotics; for example, bacteria develop more resistance to small-molecule antibiotics than to AMPs. The interaction of the AMPs with the lipopolysaccharide (LPS) layer of the Gram-negative bacteria cell envelope is not well understood. A MARTINI model was constructed of a Gram-negative bacterial outer membrane interacting with the AMP Magainin 2. In a 20 µs molecular dynamics (MD) simulation, the AMP diffused to the LPS layer of the cell envelope and remained there, suggesting interactions between the Magainin 2 and the LPS layer, causing the AMP to concentrate at that position. The free energy profile for the insertion of the Magainin 2 into the membrane was also calculated using umbrella sampling, which showed that the AMP positioned such that the cationic side chains of the AMP coordinated to the negatively charged phosphate groups of the LPS layer. These simulations indicate that the AMP Magainin 2 partition into the LPS layer of a bacterial membrane.

Network properties of intracortical myelin associated with psychosocial functioning in bipolar I disorder.

OBJECTIVE: Psychosocial functioning in bipolar disorder (BD) persists even during euthymia and has repeatedly been associated with illness progression and cognitive function. Its neurobiological correlates remain largely unexplored. Using a structural covariance approach, we explored whole cortex intracortical myelin (ICM) and psychosocial functioning in 39 BD type I and 58 matched controls. METHOD: T1 -weighted images (3T) optimized for ICM measurement were analyzed using a surface-based approach. The ICM signal was sampled at cortical mid-depth using the MarsAtlas parcellation, and psychosocial functioning was measured via the Functioning Assessment Short Test (FAST). Following construction of structural covariance matrices, graph theoretical measures were calculated for each subject. Within BD and HC groups separately, correlations between network measures and FAST were explored. After accounting for multiple comparisons, significant correlations were tested formally using rank-based regressions accounting for sex differences. RESULTS: In BD only, psychosocial functioning was associated with global efficiency (ß = -0.312, pcorr  = 0.03), local efficiency in the right rostral dorsolateral prefrontal cortex (ß = 0.545, pcorr  = 0.001) and clustering coefficient in this region (ß = 0.497, pcorr  = 0.0002) as well as in the right ventromedial prefrontal cortex (ß = 0.428, pcorr  = 0.002). All results excepting global efficiency remained significant after accounting for severity of depressive symptoms. In contrast, no significant associations between functioning and network measures were observed in the HC group. CONCLUSION: These results uncovered a novel brain-behaviour relationship between intracortical myelin signal changes and psychosocial functioning in BD.

Significant Reduction in Vaccine-Induced Antibody Levels and Neutralization Activity Among Healthcare Workers and Nursing Home Residents 6 Months Following Coronavirus Disease 2019 BNT162b2 mRNA Vaccination.

Antibody decline occurred from 2 weeks to 6 months post-BNT162b2 mRNA vaccination in nursing home (NH) residents and healthcare workers. Antispike, receptor-binding domain, and neutralization levels dropped >81% irrespective of prior infection. Notably, 69% of infection-naive NH residents had neutralizing antibodies at or below the assay's limit of detection.

A pathogenic deletion in Forkhead Box L1 (FOXL1) identifies the first otosclerosis (OTSC) gene.

Otosclerosis is a bone disorder of the otic capsule and common form of late-onset hearing impairment. Considered a complex disease, little is known about its pathogenesis. Over the past 20 years, ten autosomal dominant loci (OTSC1-10) have been mapped but no genes identified. Herein, we map a new OTSC locus to a 9.96 Mb region within the FOX gene cluster on 16q24.1 and identify a 15 bp coding deletion in Forkhead Box L1 co-segregating with otosclerosis in a Caucasian family. Pre-operative phenotype ranges from moderate to severe hearing loss to profound sensorineural loss requiring a cochlear implant. Mutant FOXL1 is both transcribed and translated and correctly locates to the cell nucleus. However, the deletion of 5 residues in the C-terminus of mutant FOXL1 causes a complete loss of transcriptional activity due to loss of secondary (alpha helix) structure. FOXL1 (rs764026385) was identified in a second unrelated case on a shared background. We conclude that FOXL1 (rs764026385) is pathogenic and causes autosomal dominant otosclerosis and propose a key inhibitory role for wildtype Foxl1 in bone remodelling in the otic capsule. New insights into the molecular pathology of otosclerosis from this study provide molecular targets for non-invasive therapeutic interventions.

Viral load and disease severity in COVID-19.

The relationship between COVID-19 severity and viral load is unknown. Our objective was to assess the association between viral load and disease severity in COVID-19. In this single center observational study of adults with laboratory confirmed SARS-CoV-2, the first positive in-hospital nasopharyngeal swab was used to calculate the log10 copies/ml [log10 copy number (CN)] of SARS-CoV-2. Four categories based on level of care and modified sequential organ failure assessment score (mSOFA) at time of swab were determined. Median log10CN was compared between different levels of care and mSOFA quartiles. Median log10CN was compared in patients who did and did not receive influenza vaccine, and the correlation between log10CN and D-dimer was examined. We found that of 396 patients, 54.3% were male, and 25% had no major comorbidity. Hospital mortality was 15.7%. Median mSOFA was 2 (IQR 0-3). Median log10CN was 5.5 (IQR 3.3-8.0). Median log10CN was highest in non-intubated ICU patients [6.4 (IQR 4.4-8.1)] and lowest in intubated ICU patients [3.6 (IQR 2.6-6.9)] (p value < 0.01). In adjusted analyses, this difference remained significant [mean difference 1.16 (95% CI 0.18-2.14)]. There was no significant difference in log10CN between other groups in the remaining pairwise comparisons. There was no association between median log10CN and mSOFA in either unadjusted or adjusted analyses or between median log10CN in patients with and without influenza immunization. There was no correlation between log10CN and D-dimer. We conclude, in our cohort, we did not find a clear association between viral load and disease severity in COVID-19 patients. Though viral load was higher in non-intubated ICU patients than in intubated ICU patients there were no other significant differences in viral load by disease severity.

Does a lack of vaccine side effects correlate with reduced BNT162b2 mRNA vaccine response among healthcare workers and nursing home residents?

BACKGROUND: The BNT162b2 SARS-CoV-2 mRNA vaccination has mitigated the burden of COVID-19 among residents of long-term care facilities considerably, despite being excluded from the vaccine trials. Data on reactogenicity (vaccine side effects) in this population are limited. AIMS: To assess reactogenicity among nursing home (NH) residents. To provide a plausible proxy for predicting vaccine response among this population. METHODS: We enrolled and sampled NH residents and community-dwelling healthcare workers who received the BNT162b2 mRNA vaccine, to assess local or systemic reactogenicity and antibody levels (immunogenicity). RESULTS: NH residents reported reactions at a much lower frequency and lesser severity than the community-dwelling healthcare workers. These reactions were mild and transient with all subjects experiencing more local than systemic reactions. Based on our reactogenicity and immunogenicity data, we developed a linear regression model predicting log-transformed anti-spike, anti-receptor-binding domain (RBD), and neutralizing titers, with a dichotomous variable indicating the presence or absence of reported reactions which revealed a statistically significant effect, with estimated shifts in log-transformed titers ranging from 0.32 to 0.37 (all p < 0.01) indicating greater immunogenicity in subjects with one or more reported reactions of varying severity. DISCUSSION: With a significantly lower incidence of post-vaccination reactions among NH residents as reported in this study, the BNT162b2 mRNA vaccine appears to be well-tolerated among this vulnerable population. If validated in larger populations, absence of reactogenicity could help guide clinicians in prioritizing vaccine boosters. CONCLUSIONS: Reactogenicity is significantly mild among nursing home residents and overall, subjects who reported post-vaccination reactions developed higher antibody titers.

Modeling the Binding and Conformational Energetics of a Targeted Covalent Inhibitor to Bruton's Tyrosine Kinase.

Targeted covalent inhibitors (TCIs) bind to their targets in both covalent and noncovalent modes, providing exceptionally high affinity and selectivity. These inhibitors have been effectively employed as inhibitors of protein kinases, with Taunton and coworkers (Nat. Chem. Biol. 2015, 11, 525-531) reporting a notable example of a TCI with a cyanoacrylamide warhead that forms a covalent thioether linkage to an active-site cysteine (Cys481) of Bruton's tyrosine kinase (BTK). The specific mechanism of the binding and the relative importance of the covalent and noncovalent interactions is difficult to determine experimentally, and established simulation methods for calculating the absolute binding affinity of an inhibitor cannot describe the covalent bond-forming steps. Here, an integrated approach using alchemical free-energy perturbation and QM/MM molecular dynamics methods was employed to model the complete Gibbs energy profile for the covalent inhibition of BTK by a cyanoacrylamide TCI. These calculations provide a rigorous and complete absolute Gibbs energy profile of the covalent modification binding process. Following a classic thiol-Michael addition mechanism, the target cysteine is deprotonated to form a nucleophilic thiolate, which then undergoes a facile conjugate addition to the electrophilic functional group to form a bond with the noncovalently bound ligand. This model predicts that the formation of the covalent linkage is highly exergonic relative to the noncovalent binding alone. Nevertheless, noncovalent interactions between the ligand and individual amino acid residues in the binding pocket of the enzyme are also essential for ligand binding, particularly van der Waals dispersion forces, which have a larger contribution to the binding energy than the covalent component in absolute terms. This model also shows that the mechanism of covalent modification of a protein occurs through a complex series of steps and that entropy, conformational flexibility, noncovalent interactions, and the formation of covalent linkage are all significant factors in the ultimate binding affinity of a covalent drug to its target.

Desulfonative Suzuki-Miyaura Coupling of Sulfonyl Fluorides.

Sulfonyl fluorides have emerged as powerful "click" electrophiles to access sulfonylated derivatives. Yet, they are relatively inert towards C-C bond forming transformations, notably under transition-metal catalysis. Here, we describe conditions under which aryl sulfonyl fluorides act as electrophiles for the Pd-catalyzed Suzuki-Miyaura cross-coupling. This desulfonative cross-coupling occurs selectively in the absence of base and, unusually, even in the presence of strong acids. Divergent one-step syntheses of two analogues of bioactive compounds showcase the expanded reactivity of sulfonyl fluorides to encompass both S-Nu and C-C bond formation. Mechanistic experiments and DFT calculations suggest oxidative addition occurs at the C-S bond followed by desulfonation to form a Pd-F intermediate that facilitates transmetalation.

Reduced BNT162b2 Messenger RNA Vaccine Response in Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2)-Naive Nursing Home Residents.

After BNT162b2 messenger RNA vaccination, antibody levels to spike, receptor-binding domain, and virus neutralization were examined in 149 nursing home residents and 110 healthcare worker controls. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-naive nursing home residents' median post-second vaccine dose antibody neutralization titers are one-quarter that of SARS-CoV-2-naive healthcare workers.