Influenza vaccine effectiveness in aged individuals: The role played by cell-mediated immunity

Effect of acupuncture therapy on vaccine-induced immune response in d-galactose-induced aging rats

Objective

This study aimed to explore whether acupuncture and moxibustion can enhance the immune response by increasing the expression of the endogenous adjuvant HSP70 mRNA.

Method

Forty Wistar rats were divided into four groups: model immune acupuncture group (A), model immune control group (B), normal immune acupuncture group (C), and normal immune control group (D). Model immune groups A and B were induced by injecting d-galactose for 6 weeks. Rats in groups A and C were then treated with low-frequency electroacupuncture (EA) at Zusanli (ST36), Guanyuan (CV4), and Baihui (GV20) and moxibustion for 3 weeks. Subsequently, all rats were observed for 2 more weeks. At the 12th week, diphtheria antitoxin titers were determined using the Vero cell trace neutralization method, CD4+T/CD8+T cell ratios in peripheral blood were examined by flow cytometry, and the relative expression of spleen cell HSP70 mRNA was measured by RT-PCR.

Results

Compared with the normal immune control, the diphtheria antitoxin titer, CD4+T/CD8+T cell ratio, and expression of spleen cell HSP70 mRNA significantly decreased in the model immune control group (P < 0.01). However, the model immune acupuncture group showed a significant increase in antitoxin titer (P < 0.01) and elevated CD4+T/CD8+T cell ratio and HSP70 mRNA expression (P < 0.05) after EA and moxibustion intervention.

Conclusion

Acupuncture and moxibustion may enhance the humoral immune response (diphtheria antitoxin titer) and cellular immune response (peripheral blood CD4+T/CD8+T cell ratio) by increasing the expression of the endogenous adjuvant HSP70 mRNA, suggesting that acupuncture may serve as a new vaccine adjuvant.

Psychological and Behavioral Predictors of Vaccine Efficacy: Considerations for COVID-19

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccine candidates are being evaluated, with the goal of conferring immunity on the highest percentage of people who receive the vaccine as possible. It is noteworthy that vaccine efficacy depends not only on the vaccine but also on characteristics of the vaccinated. Over the past 30 years, a series of studies has documented the impact of psychological factors on the immune system's vaccine response. Robust evidence has demonstrated that stress, depression, loneliness, and poor health behaviors can impair the immune system's response to vaccines, and this effect may be greatest in vulnerable groups such as the elderly. Psychological factors are also implicated in the prevalence and severity of vaccine-related side effects. These findings have generalized across many vaccine types and therefore may be relevant to the SARS-CoV-2 vaccine. In this review, we discuss these psychological and behavioral risk factors for poor vaccine responses, their relevance to the COVID-19 pandemic, as well as targeted psychological and behavioral interventions to boost vaccine efficacy and reduce side effects. Recent data suggest these psychological and behavioral risk factors are highly prevalent during the COVID-19 pandemic, but intervention research suggests that psychological and behavioral interventions can increase vaccine efficacy.

It runs in the family - Influenza vaccination and spillover effects

We study a population-based influenza vaccination program in the Netherlands, and the spillovers it has within families. Individuals aged 65 years and over qualify for the program and receive a personal invitation for a free flu shot, while ineligible individuals have to pay out-of-pocket and face additional barriers to getting vaccinated. The quasi-random variation at age 65 is exploited to analyse program impact on vaccination behavior of cohabiting partners and adult children. We find that the program induced a 10 percentage points increase in vaccination coverage among individuals at age 65. The program further led to a similar effect on vaccination take-up by cohabiting younger partners, but spillovers on children were negative. These asymmetric patterns of vaccination uptake are consistent with partners and children learning about influenza mortality risk, target group membership, and cost and benefits of vaccination, as well as salience. We conclude that public health campaigns should pay attention to the effects on voluntary preventive care participation as within-family spillovers impact the program's overall public health impact.

Vitamin D, leptin and impact on immune response to seasonal influenza A/H1N1 vaccine in older persons

BACKGROUND

Influenza-related complications are highest in the elderly. Vaccine efficacy is lower due to immunosenescence. Vitamin D's immunomodulatory role was studied in the context of vaccine response.

METHODS

We evaluated the effect of baseline 25-(OH) D on vaccine-induced immunological response in a cohort of 159 healthy subjects ages 50-74 in Rochester, MN, who received one dose of seasonal trivalent 2010-2011 influenza vaccine, containing A/California/H1N1- like virus. We examined correlations between 25-(OH) D, leptin, and leptin-related gene SNPs to understand the role of leptin and vitamin D's effects.

RESULTS

The median (IQR) baseline for total 25-(OH) D was 44.4 ng/mL (36.6-52.2 ng/mL). No correlation was observed with age. No correlation between 25-(OH) D levels and humoral immune outcomes existed at any timepoint. There was a weak positive correlation between 25-(OH) D levels and change (Day 75-Day 0) in influenza-specific granzyme-B response (r=0.16, p=0.04). We found significant associations between 3 SNPs in the PPARG gene and 25-(OH) D levels (rs1151996, p=0.01; rs1175540, p= 0.02; rs1175544, p=0.03).

CONCLUSION

Several SNPs in the PPARG gene were significantly associated with baseline 25-(OH) D levels. Understanding the functional and mechanistic relationships between vitamin D and influenza vaccine-induced immunity could assist in directing new influenza vaccine design.

Reversing T cell immunosenescence: why, who, and how

Immunosenescence is the term commonly used to describe the multifaceted phenomenon encompassing all changes occurring in the immune system during aging. It contributes to render older adults more prone to develop infectious disease and main age-related diseases. While age clearly imposes drastic changes in immune physiology, older adults have heterogeneous health and immune phenotypes. This confronts scientists and researcher to develop more age-specific interventions rather than simply adopting intervention regimes used in younger people and this in order to maintain immune protection in older adults. Thus, this review provides evidences of the central role played by cell-mediated immunity in the immunosenescence process and explores the means by which senescent state of the cell-mediated immune function could be identified and predicted using biomarkers. Furthermore considerations are given to recent advances made in the field of age-specific immune interventions that could contribute to maintain immune protection, to improve quality of life, and/or to promote healthy aging of the growing part of the population.

Immunosenescence and herd immunity: with an ever-increasing aging population do we need to rethink vaccine schedules?

Vaccination is a powerful public health tool that has been of tremendous benefit in protecting vulnerable populations from specific infections. Moreover, in addition to the direct benefits to vaccinated individuals, the indirect effects of protection at the community level have also been demonstrated and termed 'herd immunity'. The predicted demographic shift in the population landscape towards an ever-increasing aging population and the evidence suggesting that older individuals produce less-than-optimal vaccine responses have raised the question of rethinking vaccine schedules. This article provides evidence that even if herd immunity might be an option to indirectly protect the aging and aged adult population, the highest priorities for the near future must be to understand how vaccine responses in older individuals can be improved, to break down the public, cultural, societal and political barriers to vaccination and to counter the antivaccination movement that inhibits the worldwide spread of lifelong immunization programs.

Influenza vaccination in the face of immune exhaustion: is herd immunity effective for protecting the elderly?

At the start of the 21st century, seasonal influenza virus infection is still a major public health concern across the world. The recent body of evidence confirms that trivalent inactivated influenza vaccines (TIVs) are not optimal within the population who account for approximately 90% of all influenza-related death: elderly and chronically ill individuals regardless of age. With the ever increasing aging of the world population and the recent fears of any pandemic influenza rife, great efforts and resources have been dedicated to developing more immunogenic vaccines and strategies for enhancing protection in these higher-risk groups. This paper describes the mechanisms that shape immune response at the extreme ages of life and how they have been taken into account to design more effective immunization strategies for these vulnerable populations. Furthermore, consideration will be given to how herd immunity may provide an effective strategy in preventing the burden of seasonal influenza infection within the aged population.

Aging adults and seasonal influenza: does the vitamin d status (h)arm the body?

Vitamin D (VitD), although originally described as an essential hormone for bone and mineral homeostasis, appears to have an active role in regulating specific facets of human immunity. Indeed, VitD has been shown to have significant effects on cytokine production and lymphocyte proliferation. Evidence that VitD affects clearance of selected pathogens is supported by epidemiological and clinical data, while its coadministration with influenza vaccine in mice enhanced both mucosal and systemic antibody responses. This paper aims to examine how VitD may contribute to limiting the burden of influenza infection in the aging and aged adults, a population in which this burden remains considerable. Furthermore, we discuss how VitD status may play a role in host resistance to influenza virus and influence the immunogenicity of the influenza vaccines currently licensed for adults aged 65 years or over by its effects on innate and adaptive immunities.