The imperative of influenza vaccines for elderly individuals-an evolving story

Transcriptomic signatures of cellular and humoral immune responses in older adults after seasonal influenza vaccination identified by data-driven clustering

PBMC transcriptomes after influenza vaccination contain valuable information about factors affecting vaccine responses. However, distilling meaningful knowledge out of these complex datasets is often difficult and requires advanced data mining algorithms. We investigated the use of the data-driven Weighted Gene Correlation Network Analysis (WGCNA) gene clustering method to identify vaccine response-related genes in PBMC transcriptomic datasets collected from 138 healthy older adults (ages 50-74) before and after 2010-2011 seasonal trivalent influenza vaccination. WGCNA separated the 14,197 gene dataset into 15 gene clusters based on observed gene expression patterns across subjects. Eight clusters were strongly enriched for genes involved in specific immune cell types and processes, including B cells, T cells, monocytes, platelets, NK cells, cytotoxic T cells, and antiviral signaling. Examination of gene cluster membership identified signatures of cellular and humoral responses to seasonal influenza vaccination, as well as pre-existing cellular immunity. The results of this study illustrate the utility of this publically available analysis methodology and highlight genes previously associated with influenza vaccine responses (e.g., CAMK4, CD19), genes with functions not previously identified in vaccine responses (e.g., SPON2, MATK, CST7), and previously uncharacterized genes (e.g. CORO1C, C8orf83) likely related to influenza vaccine-induced immunity due to their expression patterns.

Utilizing population variation, vaccination, and systems biology to study human immunology

The move toward precision medicine has highlighted the importance of understanding biological variability within and across individuals in the human population. In particular, given the prevalent involvement of the immune system in diverse pathologies, an important question is how much and what information about the state of the immune system is required to enable accurate prediction of future health and response to medical interventions. Towards addressing this question, recent studies using vaccination as a model perturbation and systems-biology approaches are beginning to provide a glimpse of how natural population variation together with multiplexed, high-throughput measurement and computational analysis can be used to uncover predictors of immune response quality in humans. Here I discuss recent developments in this emerging field, with emphasis on baseline correlates of vaccination responses, sources of immune-state variability, as well as relevant features of study design, data generation, and computational analysis.

Comparative effectiveness of high-dose versus standard-dose influenza vaccination in community-dwelling veterans

BACKGROUND

Influenza is a significant cause of morbidity and mortality in older adults. High-dose (HD) trivalent inactivated vaccine has increased immunogenicity in older adults compared with standard-dose (SD) vaccine. We assessed the relative effectiveness of HD influenza vaccination (vs SD influenza vaccination).

METHODS

We conducted a retrospective cohort study among patients who receive primary care at Veteran Health Administration (VHA) medical centers, and who received influenza vaccine in the 2010-2011 influenza season. The primary outcome was hospitalization for influenza or pneumonia. We also conducted an analysis in subgroups defined by age.

RESULTS

We evaluated 25 714 patients who received HD vaccine and 139 511 who received SD vaccine in 23 VHA medical centers. The rate of hospitalization for influenza or pneumonia was 0.3% in both groups in the influenza season. After accounting for patient characteristics in propensity-adjusted analyses, the risk of hospitalization for influenza or pneumonia was not significantly lower among patients receiving HD vaccine vs those receiving SD vaccine (risk ratio, 0.98; 95% confidence interval, .68-1.40). In the subgroup of patients ≥85 years of age, receiving HD (compared with SD) vaccine was associated with lower rates of hospitalization for influenza or pneumonia.

CONCLUSIONS

HD vaccine was not found to be more effective than SD vaccine in protecting against hospitalization for influenza or pneumonia; however, we found a protective effect in the oldest subgroup of patients. Additional studies are needed to evaluate the effectiveness of HD vaccine.

[Flu vaccination in the elderly]

Seasonal flu is a very serious public health problem in the elderly due to its morbidity and mortality and financial and social costs arising from this. The aim of this review is to describe the magnitude and importance of seasonal flu in this population group, and its prevention by means of vaccination. For this reason, an updated account of the composition of the vaccine, its dosage and administration route, vaccine safety and the evaluation of the immunogenicity and effectiveness of vaccination. There is variation between different countries and official organisations on the age at which flu vaccination must be established in the elderly. New flu vaccination strategies need to be introduced, to further improve flu vaccination cover in Spain.

Immunopotentiation of trivalent influenza vaccine when given with VAX102, a recombinant influenza M2e vaccine fused to the TLR5 ligand flagellin

Background

Currently controversy exists about the immunogenicity of seasonal trivalent influenza vaccine in certain populations, especially the elderly. STF2.4×M2e (VAX102) is a recombinant fusion protein that links four copies of the ectodomain of influenza virus matrix protein 2 (M2e) antigen to Salmonella typhimurium flagellin, a TLR5 ligand. The objectives of this study were to assess the feasibility of giving VAX102 and TIV in combination in an effort to achieve greater immunogenicity and to provide cross-protection.

Methodology/Principal Findings

Eighty healthy subjects, 18-49 years old, were enrolled in May and June 2009 in a double-blind, randomized, controlled trial at two clinical sites. Subjects were randomized to receive either TIV + VAX102 or TIV + placebo. Both arms tolerated the vaccines. Pain at the injection site was more severe with TIV + VAX102. Two weeks after immunization the HAI responses to the H1 and H3 antigens of TIV were higher in those that received TIV + VAX102 than in TIV + placebo (309 vs 200 and 269 vs 185, respectively), although statistically non-significant. There was no difference in the HAI of the B antigen. In the TIV + VAX102 arm, the geometric mean M2e antibody concentration was 0.5 µg/ml and 73% seroconverted.

Conclusions/Significance

The combination of TIV + VAX102 has the potential to increase the immune response to the influenza A components of TIV and to provide M2e immunity which may protect against influenza A strains not contained in seasonal TIV.

Trial Registration

ClinicalTrials.gov NCT00921973