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

Safety of COVID-19 vaccination in women undergoing IVF/ICSI treatment - Clinical study and systematic review

Background

It was suggested that vaccination in general might affect reproductive health. Safety of COVID-19 vaccination in women undergoing assisted reproductive techniques (ART) treatment is not well established.

Methods

We performed a retrospective study including 536 women undergoing fresh embryo transfer after IVF/ICSI treatment in a huge IVF center in southern China to investigate the effect of COVID-19 vaccination on oocyte maturation, fertilization rate, blastulation rate, implantation rate, clinical pregnancy rate and miscarriage rate. In addition, we performed a systematic review of existing studies on the safety of COVID-19 vaccination in women undergoing ART treatment.

Results

In our study, 268 women received inactivated or recombinant COVID-19 vaccination and 268 controls were enrolled based on propensity score matching. We observed a decreased fertilization rate and signs for impaired oocyte maturation in vaccinated women. Besides our study, there were 15 studies analyzing the safety of COVID-19 vaccination in women undergoing ART treatment. For the mRNA vaccines, no adverse signals were reported concerning oocyte maturation, fertilization rate, blastulation rate, implantation rate, clinical pregnancy rate and miscarriage rate. In women being vaccinated with an inactivated vaccine, implantation rate, clinical pregnancy rate and miscarriage rate were not affected, whereas oocyte maturation and fertilization rate were impaired.

Conclusions

Vaccination against COVID-19 in women undergoing ART treatment seems to be safe especially for women getting mRNA vaccines. The effects on oocyte maturation and fertilization rate of inactivated and recombinant COVID-19 vaccinations might be a safety signal and need further investigation and independent confirmation.

Peripheral double negative T: A look at senescent Cubans

INTRODUCTION

Age-related changes in the immune system are called immunosenescence. Within the T lymphocytes is the subpopulation of double negative (DNT) peripheral lymphocytes that are immunomodulators of the immune response, based on their ability to suppress the functions of simple positive T cells and their cytotoxicity for tumor cells and those infected by viruses.

OBJECTIVE

To determine the frequency of peripheral DNT lymphocytes in older Cuban adults.

METHODS

A cross-sectional study was carried out in 30 older adults, residents in Cuba. DNT lymphocytes in peripheral blood were quantified by flow cytometry. A Beckman Coulter Gallios flow cytometer was used for data reading and analysis. Percentage values mean and standard deviation were used. The Chi-square was used to relate the percentage values of DNT and comorbidities. It was considered statistically significant if p ≤ 0.05.

RESULTS

There was a predominance of women who represented 70 %. No older adult with low values of DNT lymphocytes was reported. Women with high percentage and absolute values of DNT lymphocytes prevailed in relation to men. In the group ≥80 years, high values in % and absolute values of DNT lymphocytes predominated. The high percentage values of DNT cells were mainly related to cardiovascular disease, and predominated in the elderly of ≥80 years old; who presented respiratory and skin infections, fundamentally. The percentage normal value in the group < 80 years was significant (p = 0.0198). The Chi-square value was 0,5995.

CONCLUSIONS

Most older adults who exhibited high percentage and absolute values of DNT lymphocytes, or a tendency to them, had some associated comorbidity, an idea that suggests that DNT cells participate in immune surveillance, defense and homeostasis based on their double identity, that is, its pathogenic or immunosuppressive phenotype according to the specific immunological microenvironment.

The Immunogenicity and Safety of Influenza Vaccines among Indonesian Older adult

BACKGROUND: Immunosenescence, frailty, sarcopenia, and Vitamin D deficiency were thought of having a negative influence on adequate immune response following vaccination. Epidemiological data related to influenza vaccination and its immunogenicity and safety in Indonesia are still scarce. AIM: This study aimed to assess the immunogenicity and safety of the influenza vaccine in older adults in Indonesia and common related conditions. METHODS: This study was a one-group, pre-test, post-test, quasi-experimental study. The vaccine used was a trivalent type. Immunogenicity was assessed according to rate of seropositivity and seroconversion based on hemagglutination inhibition antibody titer. Immunization safety was assessed according to adverse events following immunization (AEFI). RESULTS: A total of 227 subjects were involved in this study. Antibody titers were significantly increased after 28-day influenza vaccination for all strains (p < 0.001). Seropositive rate in 28-day post-vaccination for A/H1N1, A/H3N2, and influenza B was 98.7%, 99.1%, and 97.4%, respectively. Meanwhile, the seroconversion rate for A/H1N1, A/H3N2, and influenza B strains was 54.2%, 66.1%, and 60.4%, respectively. The conditions of the frailty status, sarcopenia, and Vitamin D level were not associated with either seroconversion or seropositive status, both at baseline and endpoint. AEFI was occurred on seven subjects (3.08%) with pain at the injection site and one subject (0.44%) with arm tenderness. CONCLUSION: Influenza vaccination showed adequate immune response and safety regardless of the frailty status, sarcopenia, or Vitamin D level. This result strengthened the importance of influenza vaccine administration in Indonesia older adults.

Relationship Between Vitamin D Level and Platelet Parameters in Children With Viral Respiratory Infections

Apart from their classical roles, both platelets and vitamin D play important roles in inflammation and infectious diseases. This study evaluated the platelet response to viral respiratory tract infection in children aged 4-16 years, 32 with influenza, 27 with non-influenza viral infection tested by nasopharyngeal swab and 21 healthy children of the same age. Blood count, including platelet count (PLT), mean platelet volume (MPV) and other platelet indices, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP) and vitamin D (vit D) levels were compared. The influenza group showed lower PLT and platelet mass (PLT^*MPV), and the non-influenza group showed significantly lower MPV, which was correlated with the vit D levels, but not CRP or ESR, and the value vit D^*MPV was significantly lower in this group. These results revealed that platelet activation in viral respiratory tract infections in children, as measured by MPV, is related to the vit D level, with differences between influenza and non-influenza infection.

CONCLUSIONS

Viral respiratory tract infection in children can diminish the platelet size most likely by suppressing the platelet activation. This response is associated with low levels of vit D. Whether the vit D status is associated with the virus-platelet immune/inflammatory process needs further investigation.

Spatial Variability in COVID-19 Mortality

COVID-19 emerged as a global pandemic in the spring of 2020. Since that time, the disease has resulted in approximately 150 million cases and 3 million deaths worldwide. However, there is significant spatial variation in the rate of mortality from COVID-19. Here, we briefly explore spatial variations in COVID-19 mortality by country groupings and propose possible explanations for the differences observed. Specifically, we find that there is a statistically significant difference in COVID-19 mortality between countries grouped into categories based on (1) developed, primarily western diets and healthcare systems; (2) "Scandinavian" countries with advanced healthcare systems and generally anti-inflammatory diets, and (3) developing countries. We do not infer causality but believe that the observed associations provide hypotheses for future research investigations. Moreover, our results add further evidence to support additional exploration of vitamin D exposure/status and COVID-19 mortality.

COVID-19 Disease and Vitamin D: A Mini-Review

Novel coronavirus disease (COVID-19) pandemic caused by SARS-CoV-2, for which there is no effective treatment except employing prevention strategies, has already instituted significant number of deaths. In this review, we provide a scientific view on the potential role of vitamin D in SARS-CoV-2 virus/COVID-19 disease. Vitamin D is well-known to play a significant role in maintaining the immune health of an individual. Moreover, it induces antimicrobial peptide expression that can decrease viral replication and regulate the levels of pro-inflammatory/anti-inflammatory cytokines. Therefore, supplementation of vitamin D has the potential to reduce the incidence, severity and the risk of death from pneumonia resulting from the cytokine storm of many viral infections including COVID-19. We suggest that supplementation of subjects at high risk of COVID-19 with vitamin D (1.000 to 3.000 IU) to maintain its optimum serum concentrations may be of significant benefit for both in the prevention and treatment of the COVID-19.

Vitamin D high doses supplementation could represent a promising alternative to prevent or treat COVID-19 infection

Although we lack enough evidence to justify supplementing with vitamin D in the prevention and treatment of COVID-19 infection, it is increasingly feasible that this hypothesis is valid. Two general underlying mechanisms should be considered. One would be the anti-infectious and immunomodulatory action that it exerts by improving intercellular barriers by stimulating innate immunity, as well as by modulating adaptive immunity. Also, vitamin D reduces the production of inflammatory cytokines, such as IL-2 and interferon-gamma (INFγ). More recently, multiple pleiotropic effects have been demonstrated on the actions of vitamin D at the anti-inflammatory and immunomodulatory level with positive results in studies with influenza, coronavirus, and other respiratory infections. An inverse relationship between serum vitamin D levels and the prevalence of the respiratory infectious disease has been described. Of interest, another mechanistic approach responds to considering the inhibition of the renin-angiotensin-aldosterone system (RAAS), which is exacerbated in COVID-19 infection because the virus binds to the enzyme ACE2, making more angiotensin II available to cause damage. Vitamin D inhibits mediators of RAAS – present in all cells of the body – and by inhibiting ACE activity and increasing ACE2, it lowers angiotensin II levels. We present studies with proposals for recommended doses of vitamin D, and although a single guideline is not specified, the possible benefits are promising. Finally, the purpose of this review is to share this idea with health professionals to ignite the debate and call for critical reflection, so that it can contribute to the undertaking of more and better clinical designs to validate the benefits of using high doses of vitamin D for the benefit of public health and especially in times of crisis for COVID-19.

Vitamin D high doses supplementation could represent a promising alternative to prevent or treat COVID-19 infection

Si bien carecemos de suficiente evidencia que justifique suplementar con vitamina D en la prevención y/o tratamiento de la infección por COVID-19, a la fecha resulta cada vez más factible que esta hipótesis sea válida. Dos mecanismos básicos generales deberían ser considerados. Uno sería la acción antiinfecciosa e inmunomoduladora que ejerce mejorando las barreras intercelulares por estímulo de la inmunidad innata, así también por modulación de la inmunidad adaptativa. También, la vitamina D reduce la producción de citoquinas inflamatorias como IL-2 e interferón gamma (INF-γ). Más recientemente se han demostrado múltiples efectos pleiotrópicos sobre las acciones de la vitamina D a nivel antiinflamatorio e inmunomodulador. Esto explica resultados positivos en estudios con influenza, coronavirus y otras infecciones respiratorias. Se ha descrito relación inversa entre niveles séricos de vitamina D y prevalencia de patología infecciosa respiratoria. De interés, otro abordaje mecanístico responde a considerar la inhibición del sistema renina-angiotensina-aldosterona, que se exacerba en la infección por COVID-19 debido a que el virus se une a la enzima ECA2, quedando disponible más angiotensina II para causar daño. La vitamina D inhibe mediadores del SRAA —presente en todas las células del organismo—, y al inhibir la actividad ECA y aumentar la ECA2, disminuye los niveles de angiotensina II. Presentamos estudios con propuestas de dosis recomendadas de vitamina D, y aunque no quede concretada una única guía, los posibles beneficios son promisorios. Finalmente, el propósito de la presente revisión es compartir esta idea con profesionales de la salud para encender el debate y llamar a la reflexión crítica, de modo tal que se pueda contribuir con el emprendimiento de diseños clínicos adecuados para validar los beneficios de utilizar altas dosis de vitamina D en beneficio de la salud pública, sobre todo en tiempos de esta emergencia por COVID-19.

Serum Vitamin D and Immunogenicity of Influenza Vaccination in the Elderly

Vaccination is the most effective preventive measure that reduces the risk of influenza and post-influenza complications. It prevents influenza-related hospitalizations and deaths in 50-60% and about 80% of patients aged over 65, respectively. There is the clinical plausibility of the association between serum vitamin D (VIT D) content and viral respiratory infections. In this study, we addressed the issue of a vitamin D modulatory effect on the immune response to seasonal influenza vaccination in elderly persons. The study comprised 96 participants aged 60-75 during the 2016/17 epidemic season. After the determination of the baseline content of VIT D and anti-hemagglutinin antibodies (H1, H3, and HB), participants were vaccinated with a trivalent vaccine. The content of the anti-hemagglutinin antibodies was rechecked 4-5 weeks afterward, showing inappreciable alterations. The negative findings of this study make the influence of serum VIT D content on the immunogenicity of influenza vaccination highly unlikely in elderly persons.

Biomodulina T partially restores immunosenescent CD4 and CD8 T cell compartments in the elderly

The changes that occur in the immune system with aging are commonly termed immunosenescence. Immunosenescence affects almost all components and functions of the immune response. The most commonly described change is a decrease in numbers and proportions of naïve T cells combined with the increase of terminally differentiated T lymphocytes, mainly affecting CD8+ T cells. The changes in the naïve T cell compartment are principally attributed to thymic involution and lifelong chronic antigen stimulation, among other triggers. Several strategies such as hormonal products, thymic peptides, or cytokines have been proposed for the restoration of the immune system. Here we show the effects of Biomodulina T (BT) on several populations of the immune system when administered to elderly patients diagnosed with recurrent respiratory infections. BT is a polypeptide fraction of bovine thymus, a Cuban product that obtained sanitary registration in 1994 for its immunomodulatory effects. We found that CD4+ naïve T, CD8+ stem cell-like memory (SCM) T, CD4+ recent thymic emigrants (RTE) T and CD4+ CD31+ naïve T cells increased with the administration of BT, whereas CD4+ and CD8+ T cells expressing PD1 decreased after the treatment with BT. Additionally, the proliferative capacity of CD4+ T cells measured by Ki67 expression, and the CD4+ T cell ability to produce IFN-γ were also improved by BT. Moreover, BT did not increase CD4+ Tregs. Altogether, these findings suggest that BT administration is a promising strategy for immune restoration in elderly patients and improvement of immunotherapeutic potential in cancer patients.

Vitamin D and Influenza-Prevention or Therapy?

Vitamin D generates many extraskeletal effects due to the vitamin D receptor (VDR) which is present in most tissues throughout the body. The possible role of vitamin D in infections is implied from its impact on the innate and adaptive immune responses. A significant effect is also the suppression of inflammatory processes. Because vitamin D could be acknowledged as a “seasonal stimulus”, as defined by R. Edgar Hope-Simpson, it would be crucial to prove it from a potential easy and cheap prophylaxis or therapy support perspective as far as influenza infections are concerned. The survey of the literature data generates some controversies and doubts about the possible role of vitamin D in the prevention of influenza virus. The most important point is to realise that the broad spectrum of this vitamin’s activity does not exclude such a possibility. According to most of the authors, more randomized controlled trials with effective, large populations are needed to explore the preventive effect of vitamin D supplementation on viral influenza infections.

The role of UV radiation and vitamin D in the seasonality and outcomes of infectious disease

The seasonality of infectious disease outbreaks suggests that environmental conditions have a significant effect on disease risk. One of the major environmental factors that can affect this is solar radiation, primarily acting through ultraviolet radiation (UVR), and its subsequent control of vitamin D production. Here we show how UVR and vitamin D, which are modified by latitude and season, can affect host and pathogen fitness and relate them to the outcomes of bacterial, viral and vector-borne infections. We conducted a thorough comparison of the molecular and cellular mechanisms of action of UVR and vitamin D on pathogen fitness and host immunity and related these to the effects observed in animal models and clinical trials to understand their independent and complementary effects on infectious disease outcome. UVR and vitamin D share common pathways of innate immune activation primarily via antimicrobial peptide production, and adaptive immune suppression. Whilst UVR can induce vitamin D-independent effects in the skin, such as the generation of photoproducts activating interferon signaling, vitamin D has a larger systemic effect due to its autocrine and paracrine modulation of cellular responses in a range of tissues. However, the seasonal patterns in infectious disease prevalence are not solely driven by variation in UVR and vitamin D levels across latitudes. Vector-borne pathogens show a strong seasonality of infection correlated to climatic conditions favoring their replication. Conversely, pathogens, such as influenza A virus, Mycobacterium tuberculosis and human immunodeficiency virus type 1, have strong evidence to support their interaction with vitamin D. Thus, UVR has both vitamin D-dependent and independent effects on infectious diseases; these effects vary depending on the pathogen of interest and the effects can be complementary or antagonistic.

Vitamin D deficiency in children with recurrent respiratory infections, with or without immunoglobulin deficiency

PURPOSE

The objective of this study was to evaluate thevitamin D concentration in patients with recurrent respiratory infections with or without immunoglobulin G, A or M (IgG, IgA, IgM) deficiency, and to find a correlation between the vitamin D concentration and the response to hepatitis B vaccination.

MATERIALS AND METHOD

The study involved 730 patients with recurrent respiratory infections. The concentration of 25-hydroxyvitamin D (25(OH)D), immunoglobulins G, A and M, anti-HBs was determined.

RESULTS

The tests showed that 11% of patients presented IgG levels below the age related reference values. Children with reduced IgG concentration were also found to have significantly lower vitamin D concentrations in comparison to children with normal IgG. Vitamin D deficiency was observed in schoolchildren between 7 and 18 years of age. No correlation was found between 25(OH)D concentration and Hbs antibody levels.

CONCLUSIONS

An investigation of a large group of patients who have recurrent infection found patients with IgG deficiency to whom special proceeding have to be performed: 1. Significantly lower vitamin D concentration observed in the group of children with IgG deficiency implicated in long-lasting monitoring of vitamin D level require adding to the practice guidelines for Central Europe 2013. 2. Intervention treatment with suitable doses of vitamin D to clarified metabolism of vitamin D has to be plan for children with IgG deficiency and significant lower vitamin D concentration.

Vitamins as influenza vaccine adjuvant components

A number of adjuvant formulations were assayed in mice immunized with 3.75 µg of A/California/7/2009 (H1N1) pdm09 influenza vaccine with vitamins A, D and/or E in emulsions or B2 and/or B9 combined with Bordetella pertussis MPLA and/or alum as adjuvants. Squalene was used as positive control, as well as MPLA with alum. The immune response was evaluated by a panel of tests, including a hemagglutination inhibition (HAI) test, ELISA for IgG, IgG1, and IgG2a and IFN-γ, IL-2, IL-6 and IL-10 quantification in splenocyte culture supernatant after stimulus with influenza antigen. Immunological memory was evaluated using a 1/10 dose booster 60 days after the first immunization followed by assessment of the response by HAI, IgG ELISA, and determination of the antibody affinity index. The highest increases in HAI, IgG1 and IgG2a titers were obtained with the adjuvant combinations containing vitamin E, or the hydrophilic combinations containing MPLA and alum or B2 and alum. The IgG1/IgG2a ratio indicates that the response to the combination of B2 with alum would have more Th2 character than the combination of MPLA with alum. In an assay to investigate the memory response, a significant increase in HAI titer was observed with a booster vaccine dose at 60 days after immunization with vaccines containing MPLA with alum or B2 with alum. Overall, of the 27 adjuvant combinations, MPLA with alum and B2 with alum were the most promising adjuvants to be evaluated in humans.

The Active Metabolite of Vitamin D3 as a Potential Immunomodulator

In the past, vitamin D was known for its classical, skeletal action as a regulator of calcium and bone homoeostasis. Currently, vitamin D was found to have a role in numerous physiological processes in the human body; thus, vitamin D has pleiotropic activity. The studies carried out in the past two decades showed the role of vitamin D in the regulation of immune system functions. Basically, these effects may be mediated not only via endocrine mechanism of circulating calcitriol but also via paracrine one (based on cell-cell communication that leads to production of signal inducing the changes in nearby/adjacent cells and modulating their differentiation or behaviour) and intracrine mechanism (the action of vitamin D inside a cell) of 1,25-dihydroxycholecalciferol (1,25(OH)2 D3 ) synthetized from its precursor 25-hydroxyvitamin D3 (25(OH)D3 ). Both vitamin D receptor (VDR) and 25-hydroxyvitamin D3 1-α-hydroxylase (CYP27B1) are expressed in several types of immune cells (i.e. antigen presenting cells, T and B cells), and thus, they are able to synthetize the bioactive form of vitamin D that modulates both the innate and adaptive immune system. This review discusses the role of vitamin D as regulator of immune system, and our understanding of how vitamin D regulates both adaptive and innate immunity as well as inflammatory cascade on the cellular level.

1α,25(OH)2 Vitamin D3 Modulates Avian T Lymphocyte Functions without Inducing CTL Unresponsiveness

1,25-Dihydroxyvitamin D3 (Vitamin D) is a naturally synthesized fat soluble vitamin shown to have immunomodulatory, anti-inflammatory and cancer prevention properties in human and murine models. Here, we studied the effects of Vitamin D on the functional abilities of avian T lymphocytes using chicken Interferon (IFN)-γ ELISPOT assay, BrdU proliferation assay, Annexin V apoptosis assay and PhosFlow for detecting phosphorylated signalling molecules. The results demonstrate that Vitamin D significantly inhibited the abilities of T lymphocytes to produce IFN-γ and proliferate in vitro (P≤0.05), but retained their ability to undergo degranulation, which is a maker for cytotoxicity of these cells. Similarly, Vitamin D did not inhibit Extracellular signal-Regulated Kinase (ERK) 1/2 phosphorylation, a key mediator in T cell signalling, in the stimulated T lymphocytes population, while reduced ERK1/2 phosphorylation levels in the unstimulated cells. Our data provide evidence that Vitamin D has immuno-modulatory properties on chicken T lymphocytes without inducing unresponsiveness and by limiting immuno-pathology can promote protective immunity against infectious diseases of poultry.

"Let there be light": the role of vitamin D in the immune response to vaccines

Vitamin D's non-skeletal actions, including immunomodulatory role, have been increasingly recognized. Of significance, many immune cells are able to synthesize a biologically active form of vitamin D from circulating 25-hydroxyvitamin D with subsequent intracrine actions, and the vitamin D receptor is broadly distributed. In this review, we discuss vitamin D's potent role in innate and adaptive immune responses and published studies evaluating the impact of serum vitamin D, vitamin D gene pathway polymorphisms or empiric vitamin D supplementation on vaccine immunogenicity. We highlight existing knowledge gaps and propose the steps needed to advance the science and answer the question of whether vitamin D may prove valuable as a vaccine adjuvant for certain vaccines against infectious diseases.

Can we translate vitamin D immunomodulating effect on innate and adaptive immunity to vaccine response?

Vitamin D (VitD), which is well known for its classic role in the maintenance of bone mineral density, has now become increasingly studied for its extra-skeletal roles. It has an important influence on the body’s immune system and modulates both innate and adaptive immunity and regulates the inflammatory cascade. In this review our aim was to describe how VitD might influence immune responsiveness and its potential modulating role in vaccine immunogenicity. In the first instance, we consider the literature that may provide molecular and genetic support to the idea that VitD status may be related to innate and/or adaptive immune response with a particular focus on vaccine immunogenicity and then discuss observational studies and controlled trials of VitD supplementation conducted in humans. Finally, we conclude with some knowledge gaps surrounding VitD and vaccine response, and that it is still premature to recommend “booster” of VitD at vaccination time to enhance vaccine response.

Vaccination in the elderly: what can be recommended?

The age-associated increased susceptibility to infectious disease would suggest that vaccination should be a route to promote healthy aging and keep our seniors autonomous and independent. While vaccination represents a cost-effective and efficient strategy at community level, the ability of the immune system to mount a protective immune response is still unpredictable at the level of the individual. Thus, at a similar age, some individuals, including the elderly, might still be 'good' responders while some other, even younger, would definitely fail to mount a protective response. In this review, the current burden of vaccine-preventable diseases in the aging and aged population will be detailed with the aim to identify the ideal vaccine candidates over the age of 50 years. This article will conclude with potential strategies to reduce, as best as possible, this burden and the imperative need to overcome barriers in extending current vaccine coverage towards to a lifelong vaccine schedule.

Vitamin D3 modulates the function of chicken macrophages

Vitamin D3 is known to modulate both innate and adaptive immune responses in mammals, but there is little information on its effects on avian immune system cells. Here, we studied the effects of vitamin D3 on chicken macrophages. Chicken macrophages expressed vitamin D receptor (VDR) and lipopolysaccharide (LPS) stimulation increased their VDR expression. Macrophages were treated with 1,25(OH)2D3 in the presence or absence of Toll-like receptor ligands, such as LPS and Pam3CSK4. Subsequently, macrophage activation was assessed by measuring nitric oxide (NO) and expression of CXCL8 and interleukin (IL)-1β. In addition, changes in major histocompatibility complex (MHC)-II and CD86 were examined. Treatment of cells with 1,25(OH)2D3 increased the ability of macrophages to respond to stimuli and produce NO, but vitamin D3 alone did not activate macrophages and resulted in the down-regulation of CD86, MHC-II, CXCL8 and IL-1β. These findings suggest that vitamin D3 has an immunomodulatory role in chicken macrophages.

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.