Safety, Effectiveness, and Immunogenicity 6 Months After BNT162B2 mRNA Vaccine in Frail Nursing Home Residents.

BACKGROUND: Elderly people who reside in long-term care facilities form a frail and vulnerable population, with multiple pathologies and high percentages of cognitive and functional disability. OBJECTIVES: The aims of this study were to assess the safety of vaccination against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in frail nursing home residents and to evaluate its effectiveness 6 months after full vaccination. DESIGN: This was an ambispective observational study. SETTING: Residents of a long-term care facility in Madrid, Spain. PARTICIPANTS: One hundred and thirty-seven nursing home residents (81.8% female, mean age 87.77 ± 8.31 years) with high comorbidity (61.3% Charlson Index ≥ 3) and frailty (75% Clinical Frail Scale ≥ 7) who received the BNT162B2 mRNA vaccine. MEASUREMENTS: Safety data were collected to evaluate the type of adverse drug reactions and their duration, severity, and causality. Immunogenicity was tested 6 months after the primary vaccination and effectiveness was evaluated by the incidence of SARS-CoV-2 infection, the number of hospital admissions, and mortality due to coronavirus disease 2019 (COVID-19). RESULTS: Safety: Of the residents, 21.9% had some adverse reaction and 5.8% had a severe or more serious adverse reaction. The most frequent adverse reactions were fatigue (13.1%), pyrexia (12.4%), and headache (7.3%). No association was observed between frailty (including a need for palliative care) and clinical, functional or cognitive status of the participants and the occurrence of adverse events. Immunogenicity and Effectiveness: After 6 months of vaccination, only one case of SARS-CoV-2 infection was confirmed in the vaccinated residents. Most of the nursing home residents presented positive serology (95.2%). Loss of immunogenicity was associated with older age (95.12 ± 3.97 vs. 87.24 ± 8.25 years; p = 0.03) and no previous COVID-19 infection (16.6% vs. 70%; p < 0.001). Binary logistic regression models did not reveal this association. CONCLUSION: The BNT162B2 vaccine is well tolerated and effective in nursing home residents, independently of their clinical, functional, cognitive, or frailty characteristics. For the most part, immunogenicity has been maintained over time, regardless of comorbidity, functional status or frailty.

Evaluation of the Novel Methotrexate Architect Chemiluminescent Immunoassay: Clinical Impact on Pharmacokinetic Monitoring.

BACKGROUND: Fluorescence polarization immunoassay (FPIA) has probably been the most widely used technique for the determination of methotrexate (MTX) concentrations in clinical laboratories. After its replacement by a novel architect chemiluminescent microparticle immunoassay (CMIA), it is essential to verify that there are no differences between the methods that can induce an error in leucovorin rescue with dire consequences for the patient. The objective of our study was to compare plasma/serum MTX measurements between CMIA and FPIA (reference method in this study) in the work conditions of a clinical pharmacokinetics unit to determine whether any difference would affect clinical decisions on the management of this drug. METHODS: FPIA on TDx/FLx and CMIA on Architect ci8200 were simultaneously used to evaluate 127 clinical samples. Within-run (20 repetitions on same day) and between-run (20 repetitions on different days) imprecision was evaluated using 6 control samples provided by the manufacturer and diluting 2 of them by 50% for 0.03 and 0.22 µmol/L, respectively. The Passing-Bablok regression method, Bland-Altman plot, and concordance correlation coefficient (CCC) were used in the statistical analysis. RESULTS: Within-run imprecision was <5% (3.6%-4.39%) and between-run imprecision <11% (2.42%-10.65%). Between-assay correlation for the studied concentration range (0.05-250 µmol/L) was CMIA = -0.026 + 1.033 FPIA (n = 127), r = 0.9963, and CCC = 0.9946. For samples <1.5 µmol/L (nondiluted) included in the assay calibration curve, the correlation was CMIA = -0.009 + 0.955 FPIA (n = 54), r = 0.9819, and CCC = 0.9807. No significant difference was observed between the measurements by the 2 assays, given that the 95% confidence interval of the ordinate at the origin included "0" (-0.020 to 0.0007), and the 95% confidence interval of the slope included 1 (0.923-1.020). The interchangeability of these assays was confirmed by Bland-Altman plot results, which showed a mean difference insignificant at concentrations <10 µmol/L. CONCLUSIONS: The correlation between methods was excellent, and Passing-Bablok regression analysis detected no virtually difference in their results. Utilization of the CMIA-Architect assay to measure MTX concentrations would therefore not affect clinical decisions on MTX management, supporting its employment in routine MTX monitoring.