Influenza vaccines may be reformulated annually because of antigenic drift in influenza viruses. However, the relationship between antigenic characteristics of circulating viruses and vaccine effectiveness (VE) is not well understood. We conducted an assessment of the effectiveness of US influenza vaccines during the 2010-2011 season.
We performed a case-control study comparing vaccination histories between subjects with acute respiratory illness with positive real-time reverse transcription polymerase chain reaction for influenza and influenza test-negative controls. Subjects with acute respiratory illness of ≤7 days duration were enrolled in hospitals, emergency departments, or outpatient clinics in communities in 4 states. History of immunization with the 2010-2011 vaccine was ascertained from vaccine registries or medical records. Vaccine effectiveness was estimated in logistic regression models adjusted for study community, age, race, insurance status, enrollment site, and presence of a high-risk medical condition.
A total of 1040 influenza-positive cases and 3717 influenza-negative controls were included from the influenza season, including 373 cases of influenza A(H1N1), 334 cases of influenza A(H3N2), and 333 cases of influenza B. Overall adjusted VE was 60% (95% confidence interval [CI], 53%-66%). Age-specific VE estimates ranged from 69% (95% CI, 56%-77%) in children aged 6 months-8 years to 38% (95% CI, -16% to 67%) in adults aged ≥65 years.
The US 2010-2011 influenza vaccines were moderately effective in preventing medically attended influenza during a season when all 3 vaccine strains were antigenically similar to circulating viruses. Continued monitoring of influenza vaccines in all age groups is important, particularly as new vaccines are introduced.
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"During a regular influenza season, about 90% of the excess deaths occur in people aged over 65. Furthermore, poor immune responses account for diminished efficacy of vaccines [82,85] . Immune senescence also results in reactivation of latent viruses, such as varicella-zoster virus, causing shingles and chronic neuralgia. "
[Show abstract][Hide abstract]ABSTRACT: This article reviews the development of the immune response through neonatal, infant and adult life, including pregnancy, ending with the decline in old age. A picture emerges of a child born with an immature, innate and adaptive immune system, which matures and acquires memory as he or she grows. It then goes into decline in old age. These changes are considered alongside the risks of different types of infection, autoimmune disease and malignancy.
Full-text · Article · Dec 2015 · Proceedings of the Royal Society B: Biological Sciences
"We used estimates that from subjects of a broad age range (e.g. 6 months or older or 18–48 yrs.) or were restricted to one of our age groups (e.g. ≥65 yrs.)              (Table 1). Up to 2010/11 we mostly used the same estimates Kostova et al.  for their analysis of cases and hospitalizations averted by influenza vaccination; however, we excluded one unpublished study (see reference 11 in ) and one study that included non-North American populations , added one study that had been published since  as well as three studies estimating VE for the three recent influenza seasons (2011/12, 2012/13 and 2013/14, respectively)   . "
"Current inactivated trivalent influenza vaccine (TIV) strategies rely on the induction of an antibody-mediated immune response specific for the antigenically varying hemagglutinin (HA) surface antigen. TIV have only moderate efficacy or effectiveness   and is particularly impeded when the circulating strain has drifted significantly from the vaccine strain. A recent meta-analysis of TIV studies found that anti-HA antibodies are only partial correlates of protection in the general population and poor correlates of protection in the elderly . "
[Show abstract][Hide abstract]ABSTRACT: Background
FP-01.1 is a novel synthetic influenza A vaccine consisting of six fluorocarbon-modified 35-mer peptides that encapsulate multiple CD4+ and CD8+ T-cell epitopes and is designed to induce an immune response across a broad population.
FP-01.1 was evaluated for safety and immunogenicity in a randomised, double-blind, placebo-controlled, dose-escalation, phase I clinical study in healthy adult volunteers (n = 49). IFNγ ELISpot assays and multicolour flow cytometry were used to characterise the immune response.
FP-01.1 was safe and well tolerated at all doses tested with a similar adverse event profile in actively vaccinated subjects compared with controls. Maximum immunogenicity was in the 150 μg/peptide dose group where a robust response (243 spots/million PBMC) was demonstrated in 75% subjects compared with 0% in placebo controls. All six peptides were immunogenic. FP-01.1 induced dual CD4+ and CD8+ T cell responses and vaccine-specific T cells cross-recognise divergent influenza strains.
This first-in-human study showed that FP-01.1 has an acceptable safety and tolerability profile and generated robust anti-viral T cell responses in a high proportion of subjects tested. The results support the further clinical testing of FP-01.1 prior to clinical, proof-of-concept, live viral challenge studies.