Zoster Vaccination in Older Adults: Efficacy and Public Health Implications

Varicella-zoster virus-related neurological complications: From infection to immunomodulatory therapies

The Varicella-zoster virus (VZV), classified as a neurotropic member of the Herpesviridae family, exhibits a characteristic pathogenicity, predominantly inducing varicella, commonly known as chickenpox, during the initial infectious phase, and triggering the reactivation of herpes zoster, more commonly recognized as shingles, following its emergence from a latent state. The pathogenesis of VZV-associated neuroinflammation involves a complex interplay between viral replication within sensory ganglia and immune-mediated responses that contribute to tissue damage and dysfunction. Upon primary infection, VZV gains access to sensory ganglia, establishing latent infection within neurons. During reactivation, the virus can spread along sensory nerves, triggering a cascade of inflammatory mediators, chemokines, and immune cell infiltration in the affected neural tissues. The role of both adaptive and innate immune reactions, including the contributions of T and B cells, macrophages, and dendritic cells, in orchestrating the immune-mediated damage in the central nervous system is elucidated. Furthermore, the aberrant activation of the natural defence mechanism, characterised by the dysregulated production of immunomodulatory proteins and chemokines, has been implicated in the pathogenesis of VZV-induced neurological disorders, such as encephalitis, myelitis, and vasculopathy. The intricate balance between protective and detrimental immune responses in the context of VZV infection emphasises the necessity for an exhaustive comprehension of the immunopathogenic mechanisms propelling neuroinflammatory processes. Despite the availability of vaccines and antiviral therapies, VZV-related neurological complications remain a significant concern, particularly in immunocompromised individuals and the elderly. Elucidating these mechanisms might facilitate the emergence of innovative immunomodulatory strategies and targeted therapies aimed at mitigating VZV-induced neuroinflammatory damage and improving clinical outcomes. This comprehensive understanding enhances our grasp of viral pathogenesis and holds promise for pioneering therapeutic strategies designed to mitigate the neurological ramifications of VZV infections.

Understanding Drivers of Vaccine Hesitancy During the COVID-19 Pandemic Among Older Adults in Jiangsu Province, China: Cross-sectional Survey

BACKGROUND

Older adults are particularly at risk from infectious diseases, including serve complications, hospitalization, and death.

OBJECTIVE

This study aimed to explore the drivers of vaccine hesitancy among older adults based on the "3Cs" (confidence, complacency, and convenience) framework, where socioeconomic status and vaccination history played the role of moderators.

METHODS

A cross-sectional questionnaire survey was conducted in Jiangsu Province, China, between June 1 and July 20, 2021. Older adults (aged ≥60 years) were recruited using a stratified sampling method. Vaccine hesitancy was influenced by the 3Cs in the model. Socioeconomic status and vaccination history processed through the item parceling method were used to moderate associations between the 3Cs and hesitancy. Hierarchical regression analyses and structural equation modeling were used to test the validity of the new framework. We performed 5000 trials of bootstrapping to calculate the 95% CI of the pathway's coefficients.

RESULTS

A total of 1341 older adults participated. The mean age was 71.3 (SD 5.4) years, and 44.7% (599/1341) of participants were men. Confidence (b=0.967; 95% CI 0.759-1.201; P=.002), convenience (b=0.458; 95% CI 0.333-0.590; P=.002), and less complacency (b=0.301; 95% CI 0.187-0.408; P=.002) were positively associated with less vaccine hesitancy. Socioeconomic status weakened the positive effect of low complacency (b=-0.065; P=.03) on low vaccine hesitancy. COVID-19 vaccination history negatively moderated the positive association between confidence (b=-0.071; P=.02) and lower vaccine hesitancy.

CONCLUSIONS

Our study identified that confidence was the more influential dimension in reducing vaccine hesitancy among older adults. COVID-19 vaccination history, as well as confidence, had a positive association with less vaccine hesitancy and could weaken the role of confidence in vaccine hesitancy. Socioeconomic status had a substitution relationship with less complacency, which suggested a competitive positive association between them on less vaccine hesitancy.

An immunologist's guide to immunosenescence and its treatment

INTRODUCTION

: The ageing process causes several changes in the immune system, although immune ageing is strongly influenced by individual immunological history, as well as genetic and environmental factors leading to inter-individual variability.

AREAS COVERED

: Here, we focused on the biological and clinical meaning of immunosenescence. Data on SARS-CoV-2 and Yellow Fever vaccine have demonstrated the clinical relevance of immunosenescence, while inconsistent results, obtained from longitudinal studies aimed at looking for immune risk phenotypes, have revealed that the immunosenescence process is highly context-dependent. Large projects have allowed the delineation of the drivers of immune system variance, including genetic and environmental factors, sex, smoking, and co-habitation. Therefore, it is difficult to identify the interventions that can be envisaged to maintain or improve immune function in older people. That suggests that drug treatment of immunosenescence should require personalized intervention. Regarding this, we discussed the role of changes in lifestyle as a potential therapeutic approach.

EXPERT OPINION

: Our review points out that age is only part of the problem of immunosenescence. Everyone ages differently because he/she is unique in genetics and experience of life and this applies even more to the immune system (immunobiography). Finally, the present review shows how appreciable results in the modification of immunosenescence biomarkers can be achieved with lifestyle modification.

Willingness to Receive COVID-19 Vaccination among Older Adults in Saudi Arabia: A Community-Based Survey

Identifying the factors driving vaccine hesitancy can improve vaccine attitudes and motivate individuals to have the recommended vaccinations. However, failure to address the issue directly, or worse, ignoring it, could deepen such concerns, resulting in lower vaccination rates, leading to elevated rates of illness and vaccine-preventable deaths among older adults. The aim of this study was to explore the rate of acceptance of the COVID-19 vaccine among older adults in Saudi Arabia, along with the associated predicting factors and reasons for hesitancy. This study extracted data from a cross-sectional online survey on the acceptability of COVID-19 vaccination in Saudi Arabia, which was conducted from 8 to 14 December 2020. The sample of the study included 488 older adults aged 50 and older. The major data analytic tools employed in the study were bivariate and multivariable regression analyses. Among the 488 participants, 214 (43.85%) reported willingness to accept the COVID-19 vaccine when available. Older men were more likely to be willing to be vaccinated (adjusted odds ratio (aOR): 2.277; 95% confidence interval (CI): 1.092-4.745) than older women. High levels of education were significantly associated with willingness to be vaccinated. Older adults who had previously refused any vaccine were less likely to take the COVID-19 vaccine (aOR: 0.358; 95% CI: 0.154-0.830). Those who expressed a high or very high level of concern related to becoming infected were more likely to accept the vaccine against COVID-19 (aOR: 4.437; 95% CI: 2.148-9.168). Adverse side effects (27.01%), and safety and efficacy concerns (22.63%) were the most commonly cited reasons for vaccine hesitancy. The vaccination acceptance rate among older adults in Saudi Arabia is low. Interventions designed specifically for older adults addressing worries and concerns related to the vaccine are of paramount importance. In particular, these interventions should be tailored to address gender-based and health literacy level differences.

Older adults' vaccine hesitancy: Psychosocial factors associated with influenza, pneumococcal, and shingles vaccine uptake

Influenza, pneumococcal disease, and shingles (herpes zoster) are more prevalent in older people. These illnesses are preventable via vaccination, but uptake is low and decreasing. Little research has focused on understanding the psychosocial reasons behind older adults' hesitancy towards different vaccines. A cross-sectional survey with 372 UK-based adults aged 65-92 years (M = 70.5) assessed awareness and uptake of the influenza, pneumococcal, and shingles vaccines. Participants provided health and socio-demographic data and completed two scales measuring the psychosocial factors associated with vaccination behaviour. Self-reported daily functioning, cognitive difficulties, and social support were also assessed. Participants were additionally given the opportunity to provide free text responses outlining up to three main reasons for their vaccination decisions. We found that considerably more participants had received the influenza vaccine in the last 12 months (83.6%), relative to having ever received the pneumococcal (60.2%) and shingles vaccines (58.9%). Participants were more aware of their eligibility for the influenza vaccine, and were more likely to have been offered it. Multivariate logistic regression analyses showed that a lower sense of collective responsibility independently predicted lack of uptake of all three vaccines. Greater calculation of disease and vaccination risk, and preference for natural immunity, also predicted not getting the influenza vaccine. For both the pneumococcal and shingles vaccines, concerns about profiteering further predicted lack of uptake. Analysis of the qualitative responses highlighted that participants vaccinated to protect their own health and that of others. Our findings suggest that interventions targeted towards older adults would benefit from being vaccine-specific and that they should emphasise disease risks and vaccine benefits for the individual, as well as the benefits of vaccination for the wider community. These findings can help inform intervention development aimed at increasing vaccination uptake in future.

The frequency of interleukin-1β-producing monocytes is significantly associated with varicella-zoster responses of nursing home residents

Previous studies have demonstrated that the status of the T cell compartment and inflammation-related factors are associated with the immunogenicity of the varicella-zoster virus (VZV) vaccine in older adults; however, little is known about the roles of other immune cell subsets known to influence the generation and maintenance of immunological memory. Responses to a live-attenuated VZV vaccine were studied in relation to peripheral blood mononuclear cell (PBMC) composition and function in a sample of 30 nursing home residents (aged 80-99 years). Interferon-gamma enzyme-linked immunospot (ELISPOT) was used to measure VZV responses at baseline and 6 weeks following vaccination, and associations were sought with the frequencies of monocytes and T, B and natural killer (NK) cells and the production and secretion of cytokines following their ex-vivo stimulation with different agents. While only the frequency of interleukin (IL)-6⁺ CD14⁺ monocytes was inversely associated with post-vaccination VZV response, amounts of IL-1β, IL-10, IL-17A and tumour necrosis factor (TNF) secreted by PBMCs and the frequency of IL-1β⁺ CD14⁺ monocytes was positively correlated with pre-vaccination VZV response. Furthermore, both bivariate correlation and causal mediation analyses supported the notion that IL-1β⁺ CD14⁺ monocytes were significant mediators of the associations between IL-1β and TNF secretion by PBMCs and pre-vaccination VZV responses. Our findings implicate a strong cytokine response mediated by inflammatory IL-1β⁺ monocytes in coordinating responses of long-lived VZV-reactive memory T cells, but with an opposing effect of IL-6⁺ CD14⁺ monocytes. Whether monocyte status promotes or inhibits the induction and/or maintenance of these memory T cells later in life has yet to be determined.

Herpes zoster in older adults in Ontario, 2002-2016: Investigating incidence and exploring equity

Older adults are at increased risk of herpes zoster (HZ) and post-herpetic neuralgia (PHN) and HZ vaccines are available to help prevent infection. The objective of our study was to provide updated data on incidence of HZ and PHN related to clinical and demographic factors in older adults to inform immunization practices. We conducted a population-based, retrospective cohort study and included all cases of HZ seen in outpatient, emergency department, and hospital settings for adults aged 65 years and over between April 1, 2002 to August 31, 2016 in Ontario, Canada. We calculated the incidence of HZ and PHN, and estimated the proportion within each subgroup that developed PHN. We also assessed incidence by neighbourhood-level income quintile before and after the availability of vaccine for private purchase. The average annual incidence of HZ in any setting was 59.0 per 10,000 older adults, with higher incidence in outpatient as opposed to hospital settings. Incidence was higher in the oldest age groups, females, and those classified as immunocompromised or frail. Relative to the pre-vaccine era, the disparities in incidence of HZ by neighbourhood-level income increased, with higher rates of HZ and PHN seen in those residing in lower income quintiles. Additional prevention efforts should be targeted toward adults who are immunocompromised, frail, and those living in lower socioeconomic quintiles. Future work should assess the impact of the zoster vaccine program with a particular focus on equity in the publicly-funded era.

The conundrum of human immune system "senescence"

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Biomarkers of human immunosenescence are discussed.

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Longitudinal studies are essential.

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Associations of immune markers in older adults with clinical outcome are context-dependent.

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There are no universal biomarkers of human immunosenescence.

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There are common age-associated changes to peripheral immune markers in humans.

There is a great deal of debate on the question of whether or not we know what ageing is (Ref. Cohen et al., 2020). Here, we consider what we believe to be the especially confused and confusing case of the ageing of the human immune system, commonly referred to as “immunosenescence”. But what exactly is meant by this term? It has been used loosely in the literature, resulting in a certain degree of confusion as to its definition and implications. Here, we argue that only those differences in immune parameters between younger and older adults that are associated in some definitive manner with detrimental health outcomes and/or impaired survival prospects should be classed as indicators of immunosenescence in the strictest sense of the word, and that in humans we know remarkably little about their identity. Such biomarkers of immunosenescence may nonetheless indicate beneficial effects in other contexts, consistent with the notion of antagonistic pleiotropy. Identifying what could be true immunosenescence in this respect requires examining: (1) what appears to correlate with age, though generality across human populations is not yet confirmed; (2) what clearly is part of a suite of canonical changes in the immune system that happen with age; (3) which subset of those changes accelerates rather than slows aging; and (4) all changes, potentially population-specific, that accelerate agig. This remains an immense challenge. These questions acquire an added urgency in the current SARS-CoV-2 pandemic, given the clearly greater susceptibility of older adults to COVID-19.