Booster vaccination in the elderly: Their success depends on the vaccine type applied earlier in life as well as on pre-vaccination antibody titers

Age-related peculiarities of antibody-mediated humoral immune response following SARS-CoV-2 infection

Thousands of articles were published about the COVID-19 disease and hundreds about the immune response. But still little is known about the features of SARS-CoV-2-specific immunity in elderly. The aim of current research was to evaluate the age-related peculiarities of antibody mediated humoral immune response following SARS-CoV-2 infection. Our study presents an intriguing divergence from the classical concept of immunosenescence, where aging has been assumed to cause poor antibody responses, reduced or inefficient vaccination, and overall blunted immune responses in elderly people. Our findings were opposite to some of these expectations; participants aged over 60 expressed elevated titers of anti-SARS-CoV-2 antibodies in comparison to younger adults. Analyzing the data of relative neutralization and avidity of anti-SARS-Cov-2 (S) antibodies we propose that although older adults produce a higher quantity of antibodies, their functional efficiency appears relatively reduced exhibiting lower neutralizing capacity and binding strength per antibody compared to younger adults. We can assume that the immune system of the elderly may require a higher level of antibody production to obtain a comparable level of protection. Our findings highlight the intricate nature of immune responses in convalescent older adults. This has particular relevance to understanding immunity and vaccine responses in different age groups.

Enhancing vaccine effectiveness in the elderly to counter antibiotic resistance: The potential of adjuvants via pattern recognition receptors

Vaccines are an effective way to prevent the emergence and spread of antibiotic resistance by preventing diseases and establishing herd immunity. However, the reduced effectiveness of vaccines in the elderly due to immunosenescence is one of the significant contributors to the increasing antibiotic resistance. To counteract this decline and enhance vaccine effectiveness in the elderly, adjuvants play a pivotal role. Adjuvants are designed to augment the effectiveness of vaccines by activating the innate immune system, particularly through pattern recognition receptors on antigen-presenting cells. To improve vaccine effectiveness in the elderly using adjuvants, it is imperative to select the appropriate adjuvants based on an understanding of immunosenescence and the mechanisms of adjuvant functions. This review demonstrates the phenomenon of immunosenescence and explores various types of adjuvants, including their mechanisms and their potential in improving vaccine effectiveness for the elderly, thereby contributing to developing more effective vaccines for this vulnerable demographic.

Decoding NAD+ Metabolism in COVID-19: Implications for Immune Modulation and Therapy

The persistent threat of COVID-19, particularly with the emergence of new variants, underscores the urgency for innovative therapeutic strategies beyond conventional antiviral treatments. Current immunotherapies, including IL-6/IL-6R monoclonal antibodies and JAK inhibitors, exhibit suboptimal efficacy, necessitating alternative approaches. Our review delves into the significance of NAD+ metabolism in COVID-19 pathology, marked by decreased NAD+ levels and upregulated NAD+-consuming enzymes such as CD38 and poly (ADP-ribose) polymerases (PARPs). Recognizing NAD+'s pivotal role in energy metabolism and immune modulation, we propose modulating NAD+ homeostasis could bolster the host's defensive capabilities against the virus. The article reviews the scientific rationale behind targeting NAD+ pathways for therapeutic benefit, utilizing strategies such as NAD+ precursor supplementation and enzyme inhibition to modulate immune function. While preliminary data are encouraging, the challenge lies in optimizing these interventions for clinical use. Future research should aim to unravel the intricate roles of key metabolites and enzymes in NAD+ metabolism and to elucidate their specific mechanisms of action. This will be essential for developing targeted NAD+ therapies, potentially transforming the management of COVID-19 and setting a precedent for addressing other infectious diseases.

Increased Burden of Pertussis Among Adolescents and Adults With Asthma or COPD in the United States, 2007 to 2019

BACKGROUND

Individuals with chronic respiratory illnesses may be at higher risk of pertussis infection and severe pertussis than those without.

RESEARCH QUESTION

What is the incidence of pertussis and pertussis complications in cohorts with preexisting asthma or COPD vs age- and sex-matched control patients from the general population in the United States?

STUDY DESIGN AND METHODS

This observational, retrospective study included individuals aged ≥ 10 years from an administrative health claims system between 2007 and 2019. Individuals with preexisting asthma or COPD were matched with control patients from the general population. The incidence of pertussis infections and pertussis-related complications were assessed overall and by age. The incidence of asthma or COPD exacerbations was also assessed before and after diagnosis of pertussis.

RESULTS

In the general population, incidence per 100,000 person-years of pertussis infection ranged from 5.33 in 2007 to 13.04 in 2012, with highest (all years) in those aged 10 to 17 years. The risk of pertussis was higher for the asthma (rate ratio, 3.57; 95% CI, 3.25-3.92) and COPD cohorts (rate ratio, 1.83; 95% CI, 1.57-2.12) than the general population. Those with asthma or COPD had a 4.12-fold (95% CI, 3.16-5.38) and 2.82-fold (95% CI, 2.14-3.27) increased risk of pertussis with complications than the general population, respectively. Exacerbations were most frequent 30 days before pertussis diagnosis (incidence rate [IR], 25%) in the asthma cohort and 30 days before (IR, 26%) and after (IR, 22%) pertussis diagnosis, remaining elevated for 180 days after diagnosis, in the COPD cohort.

INTERPRETATION

Among these insured individuals, asthma or COPD increased the risk for pertussis disease and complications vs the general population. COPD and asthma exacerbations were observed most frequently within 30 days of receiving a pertussis diagnosis and remained elevated, suggesting a long-term effect of pertussis in the COPD cohort.

Challenges in the Vaccination of the Elderly and Strategies for Improvement

In recent years, the elderly has become a rapidly growing proportion of the world's population as life expectancy is extending. Immunosenescence and inflammaging contribute to the increased risk of chronic non-communicable and acute infectious diseases. Frailty is highly prevalent in the elderly and is associated with an impaired immune response, a higher propensity to infection, and a lower response to vaccines. Additionally, the presence of uncontrolled comorbid diseases in the elderly also contributes to sarcopenia and frailty. Vaccine-preventable diseases that threaten the elderly include influenza, pneumococcal infection, herpes zoster, and COVID-19, which contribute to significant disability-adjusted life years lost. Previous studies had shown that conventional vaccines only yielded suboptimal protection that wanes rapidly in a shorter time. This article reviews published papers on several vaccination strategies that were developed for the elderly to solve these problems: more immunogenic vaccine formulations using larger doses of antigen, stronger vaccine adjuvants, recombinant subunit or protein conjugated vaccines, newly developed mRNA vaccines, giving booster shots, and exploring alternative routes of administration. Included also are several publications on senolytic medications under investigation to boost the immune system and vaccine response in the elderly. With all those in regard, the currently recommended vaccines for the elderly are presented.

Immunosenescence and inflamm-ageing in COVID-19

The destructive effects of coronavirus disease 2019 (COVID-19) on the elderly and people with cardiovascular disease have been proven. New findings shed light on the role of aging pathways on life span and health age. New therapies that focus on aging-related pathways may positively impact the treatment of this acute respiratory infection. Using new therapies that boost the level of the immune system can support the elderly with co-morbidities against the acute form of COVID-19. This article discusses the effect of the aging immune system against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and the pathways affecting this severity of infection.

Vaccination of older adults: Influenza, pneumococcal disease, herpes zoster, COVID-19 and beyond

Preserving good health in old age is of utmost importance to alleviate societal, economic and health care-related challenges caused by an aging society. The prevalence and severity of many infectious diseases is higher in older adults, and in addition to the acute disease, long-term sequelae, such as exacerbation of underlying chronic disease, onset of frailty or increased long-term care dependency, are frequent. Prevention of infections e.g. by vaccination is therefore an important measure to ensure healthy aging and preserve quality of life. Several vaccines are specifically recommended for older adults in many countries, and in the current SARS-CoV-2 pandemic older adults were among the first target groups for vaccination due to their high risk for severe disease. This review highlights clinical data on the influenza, Streptococcus pneumoniae and herpes zoster vaccines, summarizes recent developments to improve vaccine efficacy, such as the use of adjuvants or higher antigen dose for influenza, and gives an overview of SARS-CoV-2 vaccine development for older adults. Substantial research is ongoing to further improve vaccines, e.g. by developing universal influenza and pneumococcal vaccines to overcome the limitations of the current strain-specific vaccines, and to develop novel vaccines against pathogens, which cause considerable morbidity and mortality in older adults, but for which no vaccines are currently available. In addition, we need to improve uptake of the existing vaccines and increase awareness for life-long vaccination in order to provide optimal protection for the vulnerable older age group.

SARS-CoV-2, COVID-19 and the Ageing Immune System

The coronavirus disease 2019 (COVID-19) pandemic is a global health threat with particular risk for severe disease and death in older adults and in adults with age-related metabolic and cardiovascular disease. Recent advances in the science of ageing have highlighted how ageing pathways control not only lifespan but also healthspan, the healthy years of life. Here, we discuss the ageing immune system and its ability to respond to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We specifically focus on the intersect of severe COVID-19 and immunosenescence to highlight pathways that may be determinant for the risk of complications and death following infection with SARS-CoV-2. New or adapted therapeutics that target ageing-associated pathways may be important tools to reduce the burden of death and long-term disability caused by this pandemic. Proposed interventions aimed at immunosenescence could enhance immune function not only in the elderly but in susceptible younger individuals as well, ultimately improving complications of severe COVID-19 for all ages.

Vaccines and Senior Travellers

Background: International tourist travel has been increasingly steadily in recent years, and looks set to reach unprecedented levels in the coming decades. Among these travellers, an increasing proportion is aged over 60 years, and is healthy and wealthy enough to be able to travel. However, senior travellers have specific risks linked to their age, health and travel patterns, as compared to their younger counterparts. Methods: We review here the risk of major vaccine-preventable travel-associated infectious diseases, and forms and efficacy of vaccination for these diseases. Results: Routine vaccinations are recommended for older persons, regardless of whether they travel or not (e.g., influenza, pneumococcal vaccines). Older individuals should be advised about the vaccines that are recommended for their age group in the framework of the national vaccination schedule. Travel-specific vaccines must be discussed in detail on a case-by-case basis, and the risk associated with the vaccine should be carefully weighed against the risk of contracting the disease during travel. Travel-specific vaccines reviewed here include yellow fever, hepatitis, meningococcal meningitis, typhoid fever, cholera, poliomyelitis, rabies, Japanese encephalitis, tick-borne encephalitis and dengue. Conclusion: The number of older people who have the good health and financial resources to travel is rising dramatically. Older travellers should be advised appropriately about routine and travel-specific vaccines, taking into account the destination, duration and purpose of the trip, the activities planned, the type of accommodation, as well as patient-specific characteristics, such as health status and current medications.

B and T Cell Immunity in Tissues and Across the Ages

B and T cells are key components of the adaptive immune system and coordinate multiple facets of immunity including responses to infection, vaccines, allergens, and the environment. In humans, B- and T-cell immunity has been determined using primarily peripheral blood specimens. Conversely, human tissues have scarcely been studied but they host multiple adaptive immune cells capable of mounting immune responses to pathogens and participate in tissue homeostasis. Mucosal tissues, such as the intestines and respiratory track, are constantly bombarded by foreign antigens and contain tissue-resident memory T (T_RM) cells that exhibit superior protective capacity to pathogens. Also, tissue-resident memory B (B_RM) cells have been identified in mice but whether humans have a similar population remains to be confirmed. Moreover, the immune system evolves throughout the lifespan of humans and undergoes multiple changes in its immunobiology. Recent studies have shown that age-related changes in tissues are not necessarily reflected in peripheral blood specimens, highlighting the importance of tissue localization and subset delineation as essential determinants of functional B and T cells at different life stages. This review describes our current knowledge of the main B- and T-cell subsets in peripheral blood and tissues across age groups.

Understanding immunosenescence and its impact on vaccination of older adults

Older adults are more susceptible to viral and bacterial infection, and experience higher incidence and severity of infectious diseases. Although vaccination is the most logical solution in preventing infectious diseases, primary vaccine responses in individuals aged ≥65 years-old fail to generate complete protection. This is presumably attributed to immunosenescence, a term that describes functional differences associated with the immune system and natural age advancement. Both the innate and adaptive immune systems experience age-related impairments that contribute to insufficient protection following vaccination. This review addresses current knowledge of age-related changes that affect vaccine responsiveness; including the deficits in innate cell functions, dampened humoral and cell-mediated immune responses, current vaccination schedules for older adults, and concludes with potential strategies for improving vaccine efficacy specifically for this age group. Due to an age-related decline in immunity and poor vaccine responses, infectious diseases remain a burden among the aged population.

Vaccination Coverage of the Elderly in Greece: A Cross-Sectional Nationwide Study

Vaccines are important for older adults, and the morbidity and mortality of vaccine-preventable diseases among older adults are high. There are limited data on vaccination coverage among elderly people in Greece. The aim of this observational study was to record the vaccination coverage for vaccines recommended by the National Vaccination Program in Greece for the elderly people ≥60 years old. Two hundred general practitioners (GPs) around the country from the primary healthcare system were invited to “participate,” and one hundred fifty from them participated in the present study. The GPs were selected using geographically stratified random sampling methodology. Two thousand and seventy-two participants participated in the present study: of which, 1043 were males and 1029 were females. The mean age of the participants was 73.3 years, and 83% vaccination coverage for flu vaccine, 49.5% for conjugate pneumococcal vaccine, and 23.5% for polysaccharide pneumococcal vaccine were recorded. In addition, the vaccination coverage for herpes zoster vaccine was 20%, while very low percentages were recorded for diphtheria, tetanus, pertussis, and polio vaccine for adults. We found significant gaps in vaccination coverage, especially with regard to pneumococcal, herpes zoster, and tetanus. On the contrary, influenza vaccination coverage was satisfactory.

Influence of immune aging on vaccine responses

Impaired vaccine responses in older individuals are associated with alterations in both the quantity and quality of the T-cell compartment with age. As reviewed herein, the T-cell response to vaccination requires a fine balance between the generation of inflammatory effector T cells versus follicular helper T (TFH) cells that mediate high-affinity antibody production in tandem with the induction of long-lived memory cells for effective recall immunity. During aging, we find that this balance is tipped where T cells favor short-lived effector but not memory or TFH responses. Consistently, vaccine-induced antibodies commonly display a lower protective capacity. Mechanistically, multiple, potentially targetable, changes in T cells have been identified that contribute to these age-related defects, including posttranscription regulation, T-cell receptor signaling, and metabolic function. Although research into the induction of tissue-specific immunity by vaccines and with age is still limited, current mechanistic insights provide a framework for improved design of age-specific vaccination strategies that require further evaluation in a clinical setting.

Expected immune recognition of COVID-19 virus by memory from earlier infections with common coronaviruses in a large part of the world population

SARS-CoV-2 is the coronavirus agent of the COVID-19 pandemic causing high mortalities. In contrast, the widely spread human coronaviruses OC43, HKU1, 229E, and NL63 tend to cause only mild symptoms. The present study shows, by in silico analysis, that these common human viruses are expected to induce immune memory against SARS-CoV-2 by sharing protein fragments (antigen epitopes) for presentation to the immune system by MHC class I. A list of such epitopes is provided. The number of these epitopes and the prevalence of the common coronaviruses suggest that a large part of the world population has some degree of specific immunity against SARS-CoV-2 already, even without having been infected by that virus. For inducing protection, booster vaccinations enhancing existing immunity are less demanding than primary vaccinations against new antigens. Therefore, for the discussion on vaccination strategies against COVID-19, the available immune memory against related viruses should be part of the consideration.

[Alterations in responses to vaccines in older people]

The aging population raises a number of public health issues including a need to address the severity and frequency of infections observed in older people. Vaccines play an important role in prevention. However, immunosenescence alters the intensity and quality of vaccine responses, thus limiting the impact of recommendations directed after 65 years for vaccination against flu, pneumococci, pertussis, tetanus and zoster. Immunosenescence, aggravated by co-morbidities, varies with age, becoming apparent after 60-65 years and more profound after 85 years. All stages of vaccine responses are affected by immunosenescence, from the innate immunity required to activate these responses to the induction of protective antibody responses and immune memory. Nevertheless, the capacity to develop new responses to primary vaccination is more affected than the ability to respond to recalls, although this is also impaired. Responses to vaccines are differentially altered depending on vaccine and age. Influenza vaccines are modestly immunogenic and several meta-analyses agree an estimate for efficacy of about 50% against virologically-proven flu and 40% against flu-related deaths. The anti-pneumococcal 23-valent non-conjugated vaccine does not induce memory while the 13-valent conjugated one does, but their efficacy are likely to be similar between 70 to 52% before 75 years. A sequential vaccination program with the 13-valent primo-vaccination followed by the 23-valent, recommended in immune-suppressed patients, is currently being studied in France. The waning of immunity to pertussis makes recalls necessary in the elderly who develop good antibody responses. Several research avenues are currently being pursued to try improve the degree of protection conferred by these vaccines in elderly.

The burden of pertussis in older adults: what is the role of vaccination? A systematic literature review

INTRODUCTION

Pertussis (whooping cough) is a vaccine-preventable disease; however, neither natural- nor vaccine-induced protection is life-long. Although generally not severe in adults, pertussis can be associated with complications in patients with chronic conditions such as asthma or chronic obstructive pulmonary disease, and can be readily transmitted to more vulnerable populations, including neonates before they complete their primary vaccination. Furthermore, as the global population ages, the health and economic burden of the disease is expected to rise. Areas covered: A systematic literature review was conducted to ascertain the current epidemiological and financial burden of pertussis in older adults and to discuss the potential value of a booster vaccination in this population. Expert commentary: Our review indicates a considerable underestimation of the pertussis burden amongst older adults. Seroprevalence studies consistently demonstrate that the reported incidence may be much lower than the actual incidence. Tetanus toxoid-reduced diphtheria toxoid and acellular pertussis vaccines are immunogenic in older adults, induce high booster responses and are well-tolerated. There is therefore a good rationale for the advocacy of booster pertussis vaccination throughout life to prevent pertussis infection and its transmission, especially in adults aged ≥50 years.

Comparative Analysis of B-Cell Receptor Repertoires Induced by Live Yellow Fever Vaccine in Young and Middle-Age Donors

Age-related changes can significantly alter the state of adaptive immune system and often lead to attenuated response to novel pathogens and vaccination. In present study we employed 5′RACE UMI-based full length and nearly error-free immunoglobulin profiling to compare plasma cell antibody repertoires in young (19–26 years) and middle-age (45–58 years) individuals vaccinated with a live yellow fever vaccine, modeling a newly encountered pathogen. Our analysis has revealed age-related differences in the responding antibody repertoire ranging from distinct IGH CDR3 repertoire properties to differences in somatic hypermutation intensity and efficiency and antibody lineage tree structure. Overall, our findings suggest that younger individuals respond with a more diverse antibody repertoire and employ a more efficient somatic hypermutation process than elder individuals in response to a newly encountered pathogen.

GM-CSF improves the immune response to the diphtheria-component in a multivalent vaccine

Multivalent tetanus and diphtheria toxoid containing vaccines belong to the most frequently applied vaccines. However, there is an imbalance in the degree of protection against the two antigens with insufficient long-term protection against diphtheria, particularly in the elderly population. We have previously reported a positive correlation between granulocyte macrophage-colony stimulating factor (GM-CSF) and the production of diphtheria-specific antibodies. Therefore, in the present study we analyzed the effects of in vivo applied recombinant GM-CSF on immunization with multivalent tetanus/diphtheria vaccine in mice of different age. In vivo application of GM-CSF lead to enhanced production of diphtheria-specific antibodies as well as more diphtheria-specific CD4⁺ T cells following vaccination with multivalent tetanus/diphtheria vaccine. In contrast, the humoral and cellular immune response to the tetanus component was unaltered. Furthermore, application of GM-CSF resulted in more splenic CD11b⁺ dendritic cells (DCs) with a higher MHC-II expression. GM-CSF also induced a stronger recruitment of CD11b⁺ DCs to the injected muscle. Most remarkably, GM-CSF was able to boost the diphtheria-specific immune response to the multivalent vaccine in aged mice. This study demonstrates that local administration of GM-CSF is able to improve immune responsiveness to the diphtheria component of multivalent tetanus/diphtheria vaccine in young and old mice. This information could be useful for the future design of vaccines for the elderly.

Impaired Immune Response to Primary but Not to Booster Vaccination Against Hepatitis B in Older Adults

Many current vaccines are less immunogenic and less effective in elderly compared to younger adults due to age-related changes of the immune system. Most vaccines utilized in the elderly contain antigens, which the target population has had previous contact with due to previous vaccination or infection. Therefore, most studies investigating vaccine-induced immune responses in the elderly do not analyze responses to neo-antigens but rather booster responses. However, age-related differences in the immune response could differentially affect primary versus recall responses. We therefore investigated the impact of age on primary and recall antibody responses following hepatitis B vaccination in young and older adults. Focused gene expression profiling was performed before and 1 day after the vaccination in order to identify gene signatures predicting antibody responses. Young (20-40 years; n = 24) and elderly (>60 years; n = 17) healthy volunteers received either a primary series (no prior vaccination) or a single booster shot (documented primary vaccination more than 10 years ago). Antibody titers were determined at days 0, 7, and 28, as well as 6 months after the vaccination. After primary vaccination, antibody responses were lower and delayed in the elderly compared to young adults. Non-responders after the three-dose primary series were only observed in the elderly group. Maximum antibody concentrations after booster vaccination were similar in both age groups. Focused gene expression profiling identified 29 transcripts that correlated with age at baseline and clustered in a network centered around type I interferons and pro-inflammatory cytokines. In addition, smaller 8- and 6-gene signatures were identified at baseline that associated with vaccine responsiveness during primary and booster vaccination, respectively. When evaluating the kinetic changes in gene expression profiles before and after primary vaccination, a 33-gene signature, dominated by IFN-signaling, pro-inflammatory cytokines, inflammasome components, and immune cell subset markers, was uncovered that was associated with vaccine responsiveness. By contrast, no such transcripts were identified during booster vaccination. Our results document that primary differs from booster vaccination in old age, in regard to antibody responses as well as at the level of gene signatures.

Clinical Trial Registration

www.clinicaltrialsregister.eu, this trial was registered at the EU Clinical Trial Register (EU-CTR) with the EUDRACT-Nr. 2013-002589-38.

Vaccines for the elderly: current use and future challenges

Age-related changes of the immune system contribute to increased incidence and severity of infections in the elderly. Vaccination is the most effective measure to prevent infections and vaccination recommendations in most countries include specific guidelines for the elderly. Vaccination against influenza and Streptococcus pneumoniae is usually recommended for persons with underlying diseases and for the elderly with heterogeneous age limits between ≥ 50 years and ≥ 65 years. Some countries also recommend vaccination against herpes zoster. Several vaccines are recommended for all adults, such as regular booster shots against tetanus/diphtheria/pertussis/polio, or for specific groups, e.g. vaccination against tick-borne encephalitis in endemic areas or travel vaccines. These are also relevant for the elderly. Most currently used vaccines are less immunogenic and effective in the elderly compared to younger adults. Potential strategies to improve their immunogenicity include higher antigen dose, alternative routes of administration, and the use of adjuvants, which were all implemented for influenza vaccines, and induce moderately higher antibody concentrations. Research on universal vaccines against influenza and S. pneumoniae is ongoing in order to overcome the limitations of the current strain-specific vaccines. Respiratory syncytial virus causes significant morbidity in the elderly. Novel vaccines against this and other pathogens, for instance bacterial nosocomial infections, have tremendous potential impact on health in old age and are intensively studied by many academic and commercial organizations. In addition to novel vaccine developments, it is crucial to increase awareness for the importance of vaccination beyond the pediatric setting, as vaccination coverage is still far from optimal for the older population.

Postbooster Antibodies from Humans as Source of Diphtheria Antitoxin

Diphtheria antitoxin for therapeutic use is in limited supply. A potential source might be affinity-purified antibodies originally derived from plasma of adults who received a booster dose of a vaccine containing diphtheria toxoid. These antibodies might be useful for treating even severe cases of diphtheria.

Lifelong Maintenance of Oral Tolerance and Immunity Profiles in Mice Depends on Early Exposure to Antigen

Oral tolerance is defined as a state of systemic hyporesponsiveness to an antigen that has been previously administered by the oral route. Many factors affect oral tolerance induction; some of them related to antigen, and some related to the animal. The age of the animal is one of the most important factors that affect oral tolerance as ageing brings many alterations in immune responses. Herein, we demonstrated that both the oral tolerance and pattern of immune reactivity triggered in early life were kept up to 15 months regarding the magnitude of antibody production, cell proliferation and cytokine profile when compared to immune responses induced in old mice. Therefore, our results corroborate with a promising proposal for prevaccination during childhood and young age, and a booster in older age, to make sure that the primary immunization in early life is not lost in aged individuals.

Impact of age and pre-existing influenza immune responses in humans receiving split inactivated influenza vaccine on the induction of the breadth of antibodies to influenza A strains

Most humans have pre-existing immunity to influenza viruses. In this study, volunteers (ages of 18-85 years) were vaccinated with split, inactivated Fluzone™ influenza vaccine in four consecutive influenza seasons from 2013 to 2016 seasons. The impact of repeated vaccination on breadth and durability of antibodies was assessed as a result of vaccine strain changes. Total IgG anti-hemagglutinin (HA) binding antibodies and hemagglutination-inhibition (HAI) activity increased in all age groups against both influenza A HA components in the vaccine post-vaccination (day 21). However, younger subjects maintained seroprotective titers to the vaccine strains, which resulted in higher seroconversion rates in the elderly, since the HAI titers in elderly subjects were more likely to decline prior to the next season. Young subjects had significant HAI activity against historical, as well as contemporary H1 and H3 vaccine strains from the mid-1980s to present. In contrast, elderly subjects had HAI activity to H1 strains from all years, but were more likely to have HAI activity to older strains from 1918-1950s. They also had a more restricted HAI profile against H3 viruses compared to young subjects recognizing H3N2 influenza viruses from the mid-2000s to present. Vaccine recipients were then categorized by whether subjects seroconverted from a seronegative or seropositive pre-vaccination state. Regardless of age, immunological recall or 'back-boosting' to antigenically related strains were associated with seroconversion to the vaccine strain. Overall, both younger and older people have the ability to mount a breadth of immune responses following influenza vaccination. This report describes how imprinting exposure differs across age groups, influences antibody cross-reactivity to past hemagglutinin antigenic variants, and shapes immune responses elicited by current split inactivated influenza vaccines. Understanding how current influenza vaccines are influenced by pre-existing immunity in people of different ages is critical for designing the next-generation of 'universal' or broadly-protective influenza vaccines.

Protection against Tetanus and Diphtheria in Europe: The impact of age, gender and country of origin based on data from the MARK-AGE Study

Due to the successful implementation of vaccination strategies early-life morbidity and mortality due to infectious disease has been reduced dramatically. Vaccines against tetanus and diphtheria are among the most frequently used vaccines worldwide, but various studies in different European countries have shown that protection against tetanus and particularly against diphtheria is unsatisfactory in adults and older persons. In this study we analyzed tetanus- and diphtheria-specific antibody concentrations in 2100 adults of different age from 6 selected European countries (Austria, Belgium, Germany, Greece, Italy, Poland) in order to investigate differences in the level of protection against tetanus and diphtheria across Europe. Our data reveal that tetanus- and diphtheria-specific antibody concentrations vary greatly between countries, which is also reflected in the percentage of persons with antibody concentrations below the protective level (0.1IU/ml), which ranged from 2 to 31% percent for tetanus and 28-63% for diphtheria. In most countries, tetanus- and diphtheria-specific antibody concentrations decrease with age. This phenomenon is more pronounced in countries with generally low antibody levels, such as Italy, Poland and Greece. Interestingly, tetanus-specific antibody concentrations are generally higher in males than in females, which is probably due to vaccination during their military service or more frequent booster vaccinations after injuries, whereas no gender-related differences were found for diphtheria-specific antibodies. In conclusion, our study demonstrates that the European population is not fully protected against tetanus and diphtheria. Measures to improve protection should include a life-long perspective on vaccination, more education to increase awareness of and compliance with vaccination guidelines, and a harmonization of recommendations and incentives across Europe.

Long-term maintenance of diphtheria-specific antibodies after booster vaccination is hampered by latent infection with Cytomegalovirus

Many currently used vaccines are less immunogenic in the elderly compared to young adults. The impact of latent infection with Cytomegalovirus (CMV) on vaccine-induced antibody responses has been discussed controversially. We have demonstrated that recall responses to diphtheria vaccination are frequently insufficient in elderly persons and that antibody concentrations decline substantially within 5 years. In the current study we show that within a cohort of healthy elderly (n = 87; median age 71 years, range 66–92) antibody responses to a booster vaccination against diphtheria do not differ between CMV-negative and CMV-positive individuals 4 weeks after vaccination.. However, the goal of diphtheria-vaccination is long-term protection and this is achieved by circulating anti-toxin antibodies. Diphtheria-specific antibody concentrations decline faster in CMV-positive compared to CMV-negative older adults leading to an increased proportion of persons without protective antibody concentrations 5 years after booster vaccination and endangering long-term protection. This finding could be relevant for vaccination schedules.

Guidelines for the prevention of travel-associated illness in older adults

International travel to the developing world is becoming more common in elderly patients (defined here as individuals greater than 65 years old). When providing pre-travel counseling, providers must appreciate the changing physiology, comorbidities, immunity and pharmacokinetics associated with the aging process to prepare elderly patients for the stressors of international travel. These guidelines present an evidence-based approach to pre-travel counseling, immunization, and pharmacology concerns unique to elderly patients seeking care in a travel clinic setting.

The in vitro MIMIC® platform reflects age-associated changes in immunological responses after influenza vaccination

Increasing research and development costs coupled with growing concerns over healthcare expenditures necessitate the generation of pre-clinical testing models better able to predict the efficacy of vaccines, drugs and biologics. An ideal system for evaluating vaccine immunogenicity will not only be reliable but also physiologically relevant, able to be influenced by immunomodulatory characteristics such as age or previous exposure to pathogens. We have previously described a fully autologous human cell-based MIMIC® (Modular IMmune In vitro Construct) platform which enables the evaluation of innate and adaptive immunity in vitro, including naïve and recall responses. Here, we establish the ability of this module to display reduced antibody production and T cell activation upon in vitro influenza vaccination of cells from elderly adults. In the MIMIC® system, we observe a 2.7-4.2-fold reduction in strain-specific IgG production to seasonal trivalent influenza vaccine (TIV) in the elderly when compared to adults, as well as an age-dependent decline in the generation of functional antibodies. A parallel decline in IgG production with increasing age was detected via short-term ex vivo stimulation of B cells after in vivo TIV vaccination in the same cohort. Using MIMIC®, we also detect a reduction in the number but not proportion of TIV-specific multifunctional CD154⁺IFNγ⁺IL-2⁺TNFα⁺ CD4⁺ T cells in elderly adults. Inefficient induction of multifunctional helper T cells with TIV stimulation in MIMIC® despite a normalized number of initial CD4⁺ T cells suggests a possible mechanism for an impaired anti-TIV IgG response in elderly adults. The ability of the MIMIC® system to recapitulate differential age-associated responses in vitro provides a dynamic platform for the testing of vaccine candidates and vaccine enhancement strategies in a fully human model including the ability to interrogate specific populations, such as elderly adults.

Primary vaccine failure to routine vaccines: Why and what to do?

There are 2 major factors responsible for vaccine failures, the first is vaccine-related such as failures in vaccine attenuation, vaccination regimes or administration. The other is host-related, of which host genetics, immune status, age, health or nutritional status can be associated with primary or secondary vaccine failures. The first describes the inability to respond to primary vaccination, the latter is characterized by a loss of protection after initial effectiveness. Our studies concentrate on the evaluation of immunological characteristics responsible for primary vaccine failures in different (risk) populations for which the underlying mechanisms are currently unknown. Here we summarise current knowledge and findings from our studies.

About 2–10% of healthy individuals fail to mount antibody levels to routine vaccines. Comparing the immune responses to different vaccines in non-responder and high-responder vaccinees revealed that hypo-responsiveness is antigen/vaccine-specific at the humoral but not at the cellular level. We found that T-regulatory as well as B-regulatory cells and the production of IL-10 are involved in non/hypo-responsiveness. Non-responsiveness increases with age and in particular vaccination to a novel vaccine in persons > 65 years is associated with a high low/non-responder rate, indicating that vaccine schedules and doses (at least for primary vaccination) should be adapted according to age.

In light of the growing number of allergic but also obese people, our current studies concentrate on these risk groups to reveal whether different vaccination approaches are necessary for optimal protection compared to healthy individuals. These studies are in line with the significant paradigm shift taking place in many fields of medical research and care, and will extend the concept of personalised medicine into the field of vaccinology.

Aging of the immune system: Focus on inflammation and vaccination

Major advances in preventing, delaying, or curing individual pathologies are responsible for an increasingly long life span in the developed parts of our planet, and indeed reaching eight to nine decades of life is nowadays extremely frequent. However, medical and sanitary advances have not prevented or delayed the underlying cause of the disparate pathologies occurring in the elderly: aging itself. The identification of the basis of the aging processes that drives the multiple pathologies and loss of function typical of older individuals is a major challenge in current aging research. Among the possible causes, an impairment of the immune system plays a major role, and indeed numerous studies have described immunological changes which occur with age. Far from the intention of being exhaustive, this review will focus on recent advances and views on the role that modifications of cell signalling and remodelling of the immune response play during human aging and longevity, paying particular attention to phenomena which are linked to the so called inflammaging process, such as dysregulation of innate immunity, altered T-cell or B-cell maturation and differentiation, as well as to the implications of immune aging for vaccination strategies in the elderly.

Booster vaccination against tetanus and diphtheria: insufficient protection against diphtheria in young and elderly adults

We have recently demonstrated that single shot vaccinations against tetanus and diphtheria do not lead to long-lasting immunity against diphtheria in elderly persons despite administration at 5 year intervals. In the present study we have immunized a group of young adults against tetanus and diphtheria to compare the pre- and 28 days post-vaccination immune responses in the young group with results of the same vaccination performed in an elderly group of a previous study. We also studied protection in both groups 5 years after vaccination. We compared antibody titers at all three time points and also analyzed the T cell responses in both age groups 5 years after vaccination. Before vaccination 9 % of the elderly persons were not protected against tetanus, and 48 % did not have protection against diphtheria. In the young group all participants were protected against tetanus, but 52 % were also unprotected against diphtheria before vaccination. 28 days after vaccination 100 % of all participants had protective antibody concentrations against tetanus and only a small percentage in each age group (<10 %) was unprotected against diphtheria. 5 years later, 100 % of both cohorts were still protected against tetanus, but 24 % of the young and 54 % of the elderly group were unprotected against diphtheria. Antibody concentrations against diphtheria measured by ELISA correlated well with their neutralizing capacity. T cell responses to tetanus and diphtheria did not differ between young and old persons. We conclude that booster vaccinations against tetanus and diphtheria according to present recommendations provide long-lasting protection only against tetanus, but not against diphtheria, independently of age. In elderly persons, the level of protection is even lower, probably due to intrinsic age-related changes within the immune system and/or insufficient vaccination earlier in life.

Adult vaccination against tetanus and diphtheria: the European perspective

Besides immunizations against influenza, Streptococcus pneumoniae and herpes zoster, which are recommended specifically for elderly people, regular booster vaccinations against tetanus, diphtheria and in some cases pertussis and polio are recommended in many European countries for adults, including elderly people. Vaccination recommendations for adults differ greatly between individual countries and coverage data is scarce. Tetanus-specific antibody concentrations are generally higher than diphtheria-specific antibodies, and a substantial proportion of adults, and particularly of elderly people, do not have protective antibody concentrations against diphtheria. Antibody levels increase upon booster vaccination in all age groups, but diphtheria-specific antibody concentrations remain below protective levels in some older individuals, even immediately after vaccination and long-term protection is frequently not achieved. Future vaccination strategies should therefore include regular and well-documented booster shots, e.g. against tetanus and diphtheria, throughout life.

Impairment of the humoral and CD4(+) T cell responses in HTLV-1-infected individuals immunized with tetanus toxoid

T cells from HTLV-1-infected individuals have a decreased ability to proliferate after stimulation with recall antigens. This abnormality may be due to the production of regulatory cytokine or a dysfunctional antigen presentation. The aims of this study were to evaluate the antibody production and cytokine expression by lymphocytes before and after immunization with tetanus toxoid (TT) and to evaluate the immune response of monocytes after stimulation with TT and frequency of dendritic cells (DC) subsets. HTLV-1 carriers (HC) and uninfected controls (UC) with negative serology for TT were immunized with TT, and the antibody titers were determined by ELISA as well as the cell activation markers expression by monocytes. The frequencies of DC subsets were determined by flow cytometry. Following immunization, the IgG anti-TT titers and the frequency of CD4(+) T cells expressing IFN-γ, TNF-α and IL-10 in response to TT were lower in the HC than in the UC. Additionally, monocytes from HC did not exhibit increased HLA-DR expression after stimulation with TT, and presented low numbers of DC subsets, therefore, it's necessary to perform functional studies with antigen-presenting cells. Collectively, our finding suggests that HC present an impairment of the humoral and CD4(+) T cell immune responses after vaccination.

The generation of memory B cells is maintained, but the antibody response is not, in the elderly after repeated influenza immunizations

The success of a vaccine in inducing a protective antibody response depends on the longevity of both long-lived plasma cells (PC) and memory B cells. We have previously shown that the in vivo antibody response to a new influenza vaccine, the ex vivo plasmablast response, the in vitro B cell function, measured by AID (activation-induced cytidine deaminase), and the transcription factor E47, are significantly associated and decreased in elderly individuals. We hypothesized that because AID is decreased in the elderly, the ability to generate memory B cells would also be decreased, but our findings here show that memory B cells are maintained in the elderly probably due to further amplification in response to repeated vaccination. We recruited young and elderly individuals immunized in at least two consecutive influenza vaccine seasons in which the influenza A viral strains H1N1 and H3N2 in the vaccine were the same as in the previous year. PBMC were cultured with CpG/IL2 to measure the frequency of IgG vaccine-specific memory B cells. Serum antibody response was measured by hemagglutination inhibition assay. Blood plasmablasts were measured by flow cytometry. Surprisingly, the frequencies of influenza vaccine-specific memory B cells and plasmablasts were similar in young and elderly individuals, but the fold-increase in serum titers after vaccination was lower in the elderly although most of the elderly were seroprotected. We then measured the transcription factor Blimp-1, considered the master regulator of PC differentiation, and found it significantly reduced in cultures of B cells from elderly versus young individuals, as well as E47/AID and IgG secretion. Taken together, these results suggest an impaired memory B cell to PC differentiation in the elderly.

Immunogenicity and safety of one dose of diphtheria, tetanus, acellular pertussis and poliomyelitis vaccine (Repevax®) followed by two doses of diphtheria, tetanus and poliomyelitis vaccine (Revaxis®) in adults aged ≥ 40 years not receiving a diphtheria- and tetanus-containing vaccination in the last 20 years

INTRODUCTION

The immunogenicity and safety of one dose of Tdap-IPV (tetanus, diphtheria, acellular pertussis and inactivated poliomyelitis vaccine) and two doses of Td-IPV (tetanus, diphtheria and inactivated poliomyelitis vaccine) were assessed in adults who had not received a diphtheria- and tetanus-containing vaccine in the last 20 years.

METHODS

This open-label, multicentre study was conducted in adults aged ≥ 40 years with no diphtheria- and tetanus-containing vaccine in the last 20 years. Participants received one dose of Tdap-IPV followed by two doses of Td-IPV (0, 1, 6 month schedule). Primary immunogenicity objectives: to demonstrate acceptable seroprotection rates (percentage of participants with antibody titre above threshold) post-dose 3 for diphtheria (≥ 0.1IU/mL by seroneutralization assay [SNA]); tetanus (≥ 0.1IU/mL by enzyme-linked immunosorbent assay [ELISA]); and poliomyelitis (≥ 8 1/dil by SNA); and to evaluate the percentage of participants with an antibody concentration ≥ 5EU/mL (by ELISA) for pertussis antigens post-dose 1. Seroprotection rates were acceptable if the lower limit of the 95% confidence interval (CI) was >95%. Percentage of participants with basic clinical immunity against diphtheria (≥ 0.01IU/mL) was also assessed. Safety (adverse events [AEs] and serious AEs) was assessed after each dose.

RESULTS

Overall, 336 participants were included (mean age: 60.2 years). Post-dose 3 seroprotection rates were: diphtheria, 94.6% (CI 91.5-96.8); tetanus and poliomyelitis, 100% (CI: 98.8-100). Percentage of participants with an antibody titre ≥ 5EU/mL against pertussis antigens was ≥ 95.8% for all five pertussis components. Basic clinical immunity against diphtheria was achieved in 100% (CI: 98.8-100) of participants. AEs were reported more frequently following vaccination with Tdap-IPV (post-dose 1: 65.3%) than with Td-IPV (post-dose 2: 48.3%; post-dose 3: 50.3%).

CONCLUSIONS

This study highlights the benefits of using Tdap-IPV followed by two doses of Td-IPV in an adult population to achieve maximal protection against diphtheria, tetanus, poliomyelitis and pertussis simultaneously.

Recall responses to tetanus and diphtheria vaccination are frequently insufficient in elderly persons

Demographic changes and a more active life-style in older age have contributed to an increasing public awareness of the need for lifelong vaccination. Currently many older persons have been vaccinated against selected pathogens during childhood but lack regular booster immunizations. The impact of regular vaccinations when started late in life was analyzed in an open, explorative trial by evaluating the immune response against tetanus and diphtheria in healthy older individuals. 252 persons aged above 60 years received a booster vaccination against tetanus, diphtheria, pertussis and polio and a subcohort (n=87) was recruited to receive a second booster vaccination against tetanus, diphtheria and pertussis 5 years later. The percentage of unprotected individuals at the time of enrollment differed substantially for tetanus (12%) and diphtheria (65%). Despite protective antibody concentrations 4 weeks after the first vaccination in almost all vaccinees, antibodies had again dropped below protective levels in 10% (tetanus) and 45% (diphtheria) of the cohort after 5 years. Protection was restored in almost all vaccinees after the second vaccination. No correlation between tetanus- and diphtheria-specific responses was observed, and antibody concentrations were not associated with age-related changes in the T cell repertoire, inflammatory parameters, or CMV-seropositivity suggesting that there was no general biological “non-responder type.” Post-vaccination antibody concentrations depended on pre-existing plasma cells and B cell memory as indicated by a strong positive relationship between post-vaccination antibodies and pre-vaccination antibodies as well as antibody-secreting cells. In contrast, antigen-specific T cell responses were not or only weakly associated with antibody concentrations. In conclusion, our findings demonstrate that single shot vaccinations against tetanus and/or diphtheria do not lead to long-lasting immunity in many elderly persons despite administration at relatively short intervals. Sufficient antigen-specific B cell memory B generated by adequate priming and consecutive booster vaccinations and/or exposure is a prerequisite for long-term protection.

How T follicular helper cells and the germinal centre response change with age

Normal ageing is accompanied by a decline in the function of the immune system that causes an increased susceptibility to infections and an impaired response to vaccination in older individuals. This results in an increased disease burden in the aged population, even with good immunisation programmes in place. The decreased response to vaccination is partly due to the diminution of the germinal centre response with age, caused by impaired T-cell help to B cells. Within the germinal centre, T-cell help is provided by a specialised subset of CD4(+) T cells; T follicular helper (Tfh) cells. Tfh cells provide survival and selection signals to germinal centre B cells, allowing them to egress from the germinal centre and become long-live plasma cells or memory B cells, and provide life-long protection against subsequent infection. This review will discuss the cellular and molecular changes in both Tfh cells and germinal centre B cells that occur with advancing age, which result in a smaller germinal centre response and a less effective response to immunisation.

Mechanistic insights into the impairment of memory B cells and antibody production in the elderly

It is well established that immunologic memory generated early in life can be maintained into old age and mediate robust anamnestic antibody responses. Little is known, however, about the initiation of memory B cells in the elderly. We have conducted a prospective analysis of the quantities and functionalities of antigen-specific B cell responses and its association with the functional helper CD4(+)T cell responses. The ability of naïve B cells from old (60-80 years) and young (20-31 years) humans to establish functional memory was examined following primary and booster vaccination with an inactivated-virus vaccine against tick-borne encephalitis. Our data show that the number of antigen-specific memory B cells generated during primary vaccination was ~3-fold lower in old than in young individuals. The maintenance and booster responsiveness of these memory B cells were not compromised, as evidenced by similar increases in specific memory B cell frequencies upon revaccination in old and young adults. In contrast, the Ab response mediated per memory B cell after revaccination was dramatically diminished in the elderly. Also, antigen-specific IL-2-positive CD4(+)T cell responses were strongly reduced in the elderly and displayed an excellent correlation with Ab titres. The data suggest that the dramatically lower antibody response in the elderly could only partially be accounted for by the reduced B cell numbers and was strongly correlated with profound functional defects in CD4 help.

Vaccines for the elderly

Vaccination is the most efficient strategy to prevent infectious disease. The increased vulnerability to infection of the elderly makes them a particularly important target population for vaccination. However, most vaccines are less immunogenic and efficient in the elderly because of age-related changes in the immune system. Vaccination against influenza, Streptococcus pneumoniae and varicella zoster virus is recommended for the elderly in many countries. Various strategies such as the use of adjuvants and novel administration routes are pursued to improve influenza vaccination for the elderly and recent developments in the field of pneumococcal vaccination led to the licensure of protein-conjugated polysaccharide vaccines containing up to 13 serotypes. As antibody titres are generally lower in the elderly and-particularly for inactivated vaccines-decline fast in the elderly, regular booster immunizations, for example against tetanus, diphtheria and, in endemic areas, tick-borne encephalitis, are essential during adulthood to ensure protection of the elderly. With increasing health and travel opportunities in old age the importance of travel vaccines for persons over the age of 60 is growing. However, little is known about immunogenicity and efficacy of travel vaccines in this age group. Despite major advances in the field of vaccinology over the last decades, there are still possibilities for improvement concerning vaccines for the elderly. Novel approaches, such as viral vectors for antigen delivery, DNA-based vaccines and innovative adjuvants, particularly toll-like receptor agonists, will help to achieve optimal protection against infectious diseases in old age.

[The vaccination of older adults: a challenge for the future!]

In developed countries, the population is getting older and the prevention of infectious diseases is therefore a major public health issue for elderly. Infectious diseases preventable by vaccination, including influenza, pneumococcal infection, pertussis, herpes zoster infections, and to a lesser extent, diphtheria and poliomyelitis, are direct or indirect causes of hospitalization. Few data are available on the proportion of vaccinated elderly, the impact of the under nutrition, or immunosenescence on the quality of the immune response to vaccination and the level of protection. The infectious diseases preventable by vaccination are considered in this article, and the epidemic risk related to infectious diseases in older adults living in community, the specific vaccine recommendations, the vaccines available in France, the vaccine coverage of elderly, factors interfering with vaccine response, and future prospects in this area.

Impact of aging on dendritic cell functions in humans

Aging is a paradox of reduced immunity and chronic inflammation. Dendritic cells are central orchestrators of the immune response with a key role in the generation of immunity and maintenance of tolerance. The functions of DCs are compromised with age. There is no major effect on the numbers and phenotype of DC subsets in aged subjects; nevertheless, their capacity to phagocytose antigens and migrate is impaired with age. There is aberrant cytokine secretion by various DC subsets with CDCs secreting increased basal level of pro-inflammatory cytokines but the response on stimulation to foreign antigens is decreased. In contrast, the response to self-antigens is increased suggesting erosion of peripheral self tolerance. PDC subset also secretes reduced IFN-α in response to viruses. The capacity of DCs to prime T cell responses is also affected. Aging thus has a profound affect on DC functions. Present review summarizes the effect of advancing age on DC functions in humans in the context of both immunity and tolerance.

Th17/Th1 biased immunity to the pneumococcal proteins PcsB, StkP and PsaA in adults of different age

Streptococcus pneumoniae is a major human pathogen, causing high morbidity and mortality in children, and also in the elderly, who are particularly susceptible to S. pneumoniae infections due to the dysregulated function of the aged immune system. As the current generation of polysaccharide vaccines do not provide sufficient protection for elderly, new vaccination strategies are urgently needed. To learn whether pneumococcal proteins are able to induce adaptive immune responses in adults in different age groups, we determined serum IgG antibody titers and T cell immunity (IFN-γ, IL-17A and IL-5 production) to three pneumococcal antigens, PcsB, StkP and PsaA, that are components of an investigational protein-based pneumococcal vaccine, IC47. Therefore, sera and PBMCs of 108 healthy adults in three different age groups (young, middle-aged and elderly) were analyzed by ELISA and ELISpot, respectively. We found naturally acquired antibodies to all three proteins in all age groups against all three antigens. However, elderly individuals had significantly lower IgG levels to PcsB and PsaA compared to those of younger donors. There was no significant age-related difference in the overall rate of T cell immunity for the three pneumococcal proteins. We found that the Th17 response was dominant in all age groups and was frequently combined with a Th1 or Th2 response in young and middle-aged subjects. However, in elderly persons there was a lower percentage of PBMC samples producing more than one cytokine upon antigenic stimulation. The narrow cytokine secretion pattern was the most striking difference between elderly and younger adult age groups. Our results demonstrate that in the majority of adults there is a naturally acquired humoral and cellular immune response to the three pneumococcal proteins tested. The dominance of the Th17 response is especially interesting in the light of new insights regarding the role of Th17 cells in mucosal protection against this pathogen.

Immunologic non-inferiority of a newly licensed inactivated trivalent influenza vaccine versus an established vaccine: a randomized study in US adults

A trivalent inactivated influenza vaccine (Fluarix (™) , GlaxoSmithKline Biologicals) was licensed under US accelerated approval regulations. We performed a randomized, observer-blind, post-approval study to demonstrate its immunological non-inferiority versus an established US-licensed vaccine (primary endpoint). Adult (including elderly) subjects received a single injection of newly-licensed vaccine (n = 923) or established vaccine (n = 922). Serum hemagglutination-inhibition titers were determined pre-vaccination and 21-28 days after vaccination. Non-inferiority was assessed by post-vaccination geometric mean titer (GMT) ratio (upper 95% confidence interval [CI] ≤ 1.5) and difference in seroconversion rate (upper 95% CI ≤ 0.1) for all three vaccine strains. Safety was monitored for 6 months. The newly-licensed vaccine was non-inferior to the established vaccine in all subjects (≥ 18 years) and in elderly subjects (≥ 65 years). Adjusted GMT ratios (established/newly-licensed) against the H1N1, H3N2 and B strains were 0.65 (95% CI: 0.58, 0.73), 0.93 (0.83, 1.04) and 1.13 (1.03, 1.25) for all subjects and 0.75 (0.67, 0.85), 0.95 (0.82, 1.09) and 1.13 (1.00, 1.27) for elderly subjects. Corresponding values for the differences in seroconversion rate (established minus newly-licensed) were -0.12 (-0.16, -0.07), -0.02 (-0.06, 0.03) and 0.01 (-0.04, 0.06) for all subjects and -0.11 (-0.16, -0.05), -0.02 (-0.07, 0.04) and 0.02 (-0.04, 0.08) for elderly subjects. The most common adverse events with both vaccines were injection site pain, fatigue and headache, and no serious adverse events or deaths were considered related; there were no clinically relevant differences between the vaccines. In conclusion, the newly-licensed vaccine was well tolerated and immunologically non-inferior to the established vaccine for all three vaccine strains in the whole population and the elderly.