Sustaining the momentum for adult vaccination post-COVID-19 to leverage the global uptake of life-course immunisation: A scoping review and call to action.

OBJECTIVES: The COVID-19 pandemic changed the adult vaccination landscape, possibly permanently. This review attempts to quantitate the magnitude of those changes. METHODS: PubMed was searched for studies on adult / life-course vaccination between 1 January 2020 until 8 November 2022. RESULTS: Twenty-one articles were identified and observations summarised as positive developments/impediments to life-course immunisation, and areas needing policy and structural reform. Unprecedented funding, international co-operation and technical advances led to COVID-19 vaccines authorised in record time. Investments in infrastructure and an expanded healthcare workforce streamlined vaccine delivery to adults. Constant media coverage and targeted messaging have improved health literacy. Conversely, the speed of vaccine development was perceived as a safety risk, and an 'infodemic' of misinformation propagated through social media negatively influenced vaccine uptake. Vaccine access and affordability remains inequitable among older adults and minority groups. CONCLUSIONS: The COVID pandemic led to an opportunity to permanently change policies, attitudes, and systems for vaccine delivery to adults to establish a global life-course approach to immunisation. This is a call for action to sustain the momentum triggered by the COVID-19 pandemic. Addressing inequalities, improving health literacy and optimally using social media are critical to sustain adult vaccinations in post-COVID-19 era.

Sustainable Dengue Prevention and Management: Integrating Dengue Vaccination Strategies with Population Perspectives.

The GEMKAP study (2023) unveiled consistent knowledge, attitude, and practice (KAP) levels across Asia-Pacific (APAC) and Latin America (LATAM) countries regarding dengue, with variations in the willingness to vaccinate. Despite an overall KAP parity, the disparities within and between the countries indicated the need for both overarching and tailored strategies. Population-wide gaps in dengue awareness result in suboptimal vaccination priorities and preventive measures. This commentary delves into identifying the drivers and barriers for implementing a multi-pronged dengue prevention and management program, emphasizing the pivotal role of vaccination alongside education and vector control. Drawing on expert interviews in APAC and LATAM, informed by the Consolidated Framework for Implementation Research (CFIR), four key themes emerged: prioritizing and continuously advocating for dengue on national health agendas, fostering stakeholder collaboration, incorporating population perspectives for behavioral change, and designing sustainable dengue prevention and management programs. Successful implementation requires evidence-based decision making and a comprehensive understanding of population dynamics to design adaptive education tailored to diverse population views. This commentary provides actionable strategies for enhancing dengue prevention and management, with a pronounced emphasis on dengue vaccination, advocating for a holistic, population-centric approach for sustained effectiveness.

Knowledge, Attitudes and Practices toward Dengue Fever, Vector Control, and Vaccine Acceptance Among the General Population in Countries from Latin America and Asia Pacific: A Cross-Sectional Study (GEMKAP).

Dengue represents a major public health concern. With effective vaccines in development, it is important to identify motivational factors to maximize dengue vaccine uptake. A cross-sectional, quantitative, electronic survey was administered to a nationally representative adult population (n = 3800) in Argentina, Brazil, Colombia, Mexico, Indonesia, Malaysia, and Singapore. Willingness to vaccinate against dengue, and Knowledge, Attitudes, and Practices (KAP) toward dengue, vector control, prevention, and vaccination were determined. The Capability, Opportunity, Motivation for Behavior change (COM-B) framework was used to identify factors correlated with dengue vaccine(s) uptake. KAP scores (standardized, 0-100% scale) resulted in a low global score for Knowledge (48%) and Practice (44%), and a moderate score for Attitude (66%); scores were comparable across countries. Of all respondents, 53% had a high willingness (Score: 8-10/10) to vaccinate against dengue, which was higher (59%) in Latin America (Argentina, Brazil, Colombia, Mexico) than in Asia Pacific (40%) (Indonesia, Malaysia, Singapore). Key factors significantly (p < 0.05) associated with increased willingness to vaccinate included accessibility to the public (subsidies and incentives) and trust in the healthcare system and government. A common approach to dengue prevention across endemic countries--with some country-specific customization, including education, vaccination, and vector control (multi-pronged)--may reduce dengue burden and improve outcomes.

The need for vaccination in adults with chronic (noncommunicable) diseases in India - lessons from around the world.

Worldwide, chronic diseases (noncommunicable diseases [NCDs]) cause 41 million (71%) deaths annually. They are the leading cause of mortality in India, contributing to 60% of total deaths each year. Individuals with these diseases are more susceptible to vaccine-preventable diseases (VPDs) and have an increased risk of associated disease severity and complications. This poses a substantial burden on healthcare systems and economies, exemplified by the COVID-19 pandemic. Vaccines are an effective strategy to combat these challenges; however, utilization rates are inadequate. With India running one of the world's largest COVID-19 vaccination programs, this presents an opportunity to improve vaccination coverage for all VPDs. Here we discuss the burden of VPDs in those with NCDs, the benefit of vaccinations, current challenges and possible strategies that may facilitate implementation and accessibility of vaccination programs. Effective vaccination will have a significant impact on the disease burden of both VPDs and NCDs and beyond.

What is already known on this topic?Annually, chronic or noncommunicable diseases (NCDs) cause >40 million deaths worldwide and 60% of all deaths in IndiaAdults with these diseases are more susceptible to vaccine-preventable diseases (VPDs); however, vaccine utilization is inadequate in this populationWhat is added by this report?We highlight the benefits of vaccination in adults with NCDs that extend beyond disease preventionWe discuss key challenges in implementing adult vaccination programs and provide practical solutionsWhat are the implications for public health practice?Raising awareness about the benefits of vaccinations, particularly for those with NCDs, and providing national guidelines with recommendations from medical societies, will increase vaccine acceptanceAdequate vaccine acceptance will reduce the VPD burden in this vulnerable population.

Vaccination in Older Adults: An Underutilized Opportunity to Promote Healthy Aging in India.

Over the last 50 years, the Indian population aged 50 years and above (older adults) has quadrupled and is expected to comprise 404 million people in 2036, representing 27% of the country's projected population. Consequently, the contribution of chronic disease to older adults' total burden of diseases in India is likely to escalate. Disease burden is notably amplified by immunosenescence, a deterioration of the immune system that develops with age, leading to increasing susceptibility to infectious diseases and other comorbidities. Older adults with infectious diseases have a higher incidence and likelihood of life-threatening comorbidities such as coronary artery disease, arrhythmia, stroke, myocardial infarction, hypertension, dyslipidemia, and diabetes mellitus. Therefore, immunization of older adults through vaccination might greatly reduce the burden imposed by vaccine preventable infectious diseases in this population. Here, we review evidence relevant to the disease burden among adults aged ≥ 50 years in India, and existing vaccination recommendations. Furthermore, we suggest a set of routine vaccinations for healthy older adults in India. There is a clear mandate to recognize the contributions of older adults to society and embrace strategies promoting healthy aging, which is described by the World Health Organization as the process of developing and maintaining functional ability and well-being in older age. Increasing vaccination awareness and coverage among older adults is an important step in that direction for India.

Correction to: Vaccine Hesitancy as a Challenge or Vaccine Confidence as an Opportunity for Childhood Immunisation in India.

In the original publication, the fourth author name was incorrectly published as Jayant Ray.

Vaccine Hesitancy as a Challenge or Vaccine Confidence as an Opportunity for Childhood Immunisation in India.

Vaccines have contributed substantially to decreasing the morbidity and mortality rates of many infectious diseases worldwide. Despite this achievement, an increasing number of parents have adopted hesitant behaviours towards vaccines, delaying or even refusing their administration to children. This has implications not only on individuals but also society in the form of outbreaks for e.g. measles, chicken pox, hepatitis A, etc. A review of the literature was conducted to identify the determinants of vaccine hesitancy (VH) as well as vaccine confidence and link them to challenges and opportunities associated with vaccination in India, safety concerns, doubts about the need for vaccines against uncommon diseases and suspicions towards new vaccines were identified as major vaccine-specific factors of VH. Lack of awareness and limited access to vaccination sites were often reported by hesitant parents. Lastly, socio-economic level, educational level and cultural specificities were contextual factors of VH in India. Controversies and rumours around some vaccines (e.g., human papillomavirus) have profoundly impacted the perception of the risks and benefits of vaccination. Challenges posed by traditions and cultural behaviours, geographical specificities, socio-demographic disparities, the healthcare system and vaccine-specific features are highlighted, and opportunities to improve confidence are identified. To overcome VH and promote vaccination, emphasis should be on improving communication, educating the new generation and creating awareness among the society. Tailoring immunisation programmes as per the needs of specific geographical areas or communities is also important to improve vaccine confidence. Fig. 1 Plain language summary.

Health Care Professionals' Perspectives on Life-Course Immunization: A Qualitative Survey from a European Conference.

Today, fewer children die each year from vaccine-preventable diseases than older adults. Health systems need new immunization strategies to tackle the burden of vaccine-preventable disease in an aging society. A life-course immunization (LCI) approach-which entails vaccination throughout an individual's lifespan-enables adults to age with reduced risk to disease, thereby enabling healthy, active and productive aging. We conducted an audience response system (ARS)-based survey to investigate HCP perspectives on LCI in an opportunistic sample of 222 health care professionals (HCPs) from around the world who attended a European infectious diseases conference. Survey results show that LCI is a priority for HCPs (77.4%-88.6%), with most of them stating the need to frame it as a part of a healthy lifestyle (91.0%-100.0%). Insufficient LCI recommendations by vaccine providers (12.9%-33.3%) and governments (15.2%-41.9%) and insufficient targeted budget allocation (6.1%-21.7%) were indicated as the main barriers to implement LCI, ahead of vaccine hesitancy (9.7%-15.2%). HCPs were willing to make LCI a gateway to healthy aging but need support to work together with other stakeholders involved in the vaccination journey. This could be a step towards equitable health care for all of society.

Towards adult vaccination in India: a narrative literature review.

Despite vast improvements in childhood vaccination coverage in India, adult vaccination coverage is negligible. Our aim was, therefore, to create awareness about the importance of adult immunization. Although the true burden of vaccine-preventable diseases (VPDs) among Indian adults is unknown, adults are particularly vulnerable during outbreaks, due to a lack of immunization, waning immunity, age-related factors (e.g. chronic conditions and immunosenescence), and epidemiological shift. There are no national adult immunization guidelines in India, and although several medical societies have published adult immunization guidelines, these vary, making it unclear who should receive which vaccines (based on age, underlying conditions, etc.). Other barriers to adult immunization include vaccine hesitancy, missed opportunities, and cost. Steps to improve adult vaccination could include: adoption of national guidelines, education of healthcare providers and the public, and promotion of life-course immunization. Improving adult vaccine coverage could help reduce the burden of VPDs, particularly among older adults.

Precision Medicine and Vaccination of Older Adults: From Reactive to Proactive (A Mini-Review).

As populations age globally, the health of older adults is looming larger on the agendas of public health bodies. In particular, the priority is to ensure that older adults remain healthy, independent, and engaged in their communities. In other words, ensuring that increasing life spans are matched by increasing "health spans," meaning years spent in good health. Chronic conditions such as cancer or respiratory and cardiovascular diseases account for the bulk of the disease burden in older adults, and the consensus is that these can best be tackled by effective primary prevention. However, given the diverse nature of older populations, whose prior health experiences can be complicated by multi-morbidity and poly-pharmacy, effective primary prevention can be challenging. One approach that is gaining momentum is what is called "precision" or P4 medicine. The acronym stands for "predictive, personalized, preventive, participatory" medicine, and is based on the premise that preventing disease is better than treating it. However, effective prevention requires the ability to predict disease risk for a given patient, the tailoring of treatment to their circumstances, and their consent for or participation in the offered treatment. A P4 approach may seem counter-intuitive, given that vaccination is generally considered a public health intervention. However, in this article, we discuss the application of P4 medicine as a complement to planning the vaccination of older individuals, with a special focus on the important role that vaccine-preventable infections play in the burden of non-communicable disease.

Pharmacy-based interventions to increase vaccine uptake: report of a multidisciplinary stakeholders meeting.

BACKGROUND: Despite the existence of efficacious vaccines, the burden of vaccine-preventable diseases remains high and the potential health benefits of paediatric, adolescent and adult vaccination are not being achieved due to suboptimal vaccine coverage rates. Based on emerging evidence that pharmacy-based vaccine interventions are feasible and effective, the European Interdisciplinary Council for Ageing (EICA) brought together stakeholders from the medical and pharmacy professions, the pharmaceutical industry, patient/ageing organisations and health authorities to consider the potential for pharmacy-based interventions to increase vaccine uptake. We report here the proceedings of this 3-day meeting held in March 2018 in San Servolo island, Venice, Italy, focussing firstly on examples from countries that have introduced pharmacy-based vaccination programmes, and secondly, listing the barriers and solutions proposed by the discussion groups. CONCLUSIONS: A range of barriers to vaccine uptake have been identified, affecting all target groups, and in various countries and healthcare settings. Ease of accessibility is a potentially modifiable determinant in vaccine uptake, and thus, improving the diversity of settings where vaccines can be provided to adults, for example by enabling community pharmacists to vaccinate, may increase the number of available opportunities for vaccination.

Adjuvant Systems for vaccines: 13 years of post-licensure experience in diverse populations have progressed the way adjuvanted vaccine safety is investigated and understood.

Adjuvant Systems (AS) are combinations of immune stimulants that enhance the immune response to vaccine antigens. The first vaccine containing an AS (AS04) was licensed in 2005. As of 2018, several vaccines containing AS04, AS03 or AS01 have been licensed or approved by regulatory authorities in some countries, and included in vaccination programs. These vaccines target diverse viral and parasitic diseases (hepatitis B, human papillomavirus, malaria, herpes zoster, and (pre)pandemic influenza), and were developed for widely different target populations (e.g. individuals with renal impairment, girls and young women, infants and children living in Africa, adults 50 years of age and older, and the general population). Clearly, the safety profile of one vaccine in one target population cannot be extrapolated to another vaccine or to another target population, even for vaccines containing the same adjuvant. Therefore, the assessment of adjuvant safety poses specific challenges. In this review we provide a historical perspective on how AS were developed from the angle of the challenges encountered on safety evaluation during clinical development and after licensure, and illustrate how these challenges have been met to date. Methods to evaluate safety of adjuvants have evolved based on the availability of new technologies allowing a better understanding of their mode of action, and new ways of collecting and assessing safety information. Since 2005, safety experience with AS has accumulated with their use in diverse vaccines and in markedly different populations, in national immunization programs, and in a pandemic setting. Thirteen years of experience using antigens combined with AS attest to their acceptable safety profile. Methods developed to assess the safety of vaccines containing AS have progressed the way we understand and investigate vaccine safety, and have helped set new standards that will guide and support new candidate vaccine development, particularly those using new adjuvants. FOCUS ON THE PATIENT: What is the context? Adjuvants are immunostimulants used to modulate and enhance the immune response induced by vaccination. Since the 1990s, adjuvantation has moved toward combining several immunostimulants in the form of Adjuvant System(s) (AS), rather than relying on a single immunostimulant. AS have enabled the development of new vaccines targeting diseases and/or populations with special challenges that were previously not feasible using classical vaccine technology. What is new? In the last 13 years, several AS-containing vaccines have been studied targeting different diseases and populations. Over this period, overall vaccine safety has been monitored and real-life safety profiles have been assessed following routine use in the general population in many countries. Moreover, new methods for safety assessment, such as a better determination of the mode of action, have been implemented in order to help understand the safety characteristics of AS-containing vaccines. What is the impact? New standards and safety experience accumulated over the last decade can guide and help support the safety assessment of new candidate vaccines during development.

Challenges facing vaccinators in the 21st century: results from a focus group qualitative study.

Introduction: Barriers to vaccination and the important role of healthcare professionals (HCPs) in influencing immunization decisions made by parents/patients have been well documented. Little information describes challenges that HCPs face in carrying out their role as vaccinators.Methods: We conducted a focus group study asking HCPs to describe their expectations as frontline vaccinators versus the day-to-day reality they faced. Participants described challenges impacting their ability and motivation as vaccinators, and proposed key solutions to the most important challenges. A total of 75 nurses and physicians (sixteen groups of frontline vaccinators) from the United Kingdom, United States, Germany and India participated in 2 hour focus-group discussions.Results: There was disconnect between how participants viewed their role in preserving population health when they started their career, and the reality of real-world practice today. Challenges experienced and reflected were similar across professional groups and countries. Low patient-level vaccine knowledge, patient miseducation, untimely vaccine information, frequently changing vaccine schedules, time pressures, lack of centralized record systems, pressure to achieve vaccination targets, and in some instances vaccine costs, all impacted the efficiency and enthusiasm of HCPs. Identified solutions by the same providers included improving patient-level information, equipping HCPs with effective information, and practical ways to reduce the vaccination burden by improved administrative processes and centralized recording coupled with delegating vaccinator roles.Conclusion: This focus group gives unique insights into needs of HCPs to fulfill their role as vaccinators. Supporting and equipping vaccinators is critical to the continuing success of vaccination programs and the proposed life-course immunization strategy. (Supplementary Appendix 1).

Life-course immunization as a gateway to health.

INTRODUCTION: Extending the benefits of vaccination against infectious diseases from childhood throughout the entire life-span is becoming an increasingly urgent priority in view of the world's aging population, emergence and reemergence of infectious diseases, and the necessity to invest more on prevention versus cure in global healthcare. Areas covered: This perspective discusses how life-course immunization could benefit human health at all stages of life. To achieve this, the current vaccination paradigm should be changed and all stakeholders have a role to play. Expert commentary: To enhance immunization confidence in the population, it is essential that stakeholders eliminate complacency toward infectious diseases, improve vaccination convenience, remove barriers among different healthcare specialties, and address prevention as a single entity. They must also consider societal and cultural mindsets by understanding and including public viewpoints. A new "4Cs' model encompassing convenience, confidence, complacency, and cultural acceptance is proposed to convert 'vaccine availability' to 'vaccination acceptance' throughout life. Life-course vaccination should become the new social norm of a healthy life-style, along with a healthy diet, adequate physical exercise, and not smoking. We are 'all in' to make life-course immunization a gateway for all people to lead longer, healthier lives.

Vaccination programs for older adults in an era of demographic change.

OBJECTIVES: Populations are aging worldwide. This paper summarizes some of the challenges and opportunities due to the increasing burden of infectious diseases in an aging population. RESULTS: Older adults typically suffer elevated morbidity from infectious disease, leading to increased demand for healthcare resources and higher healthcare costs. Preventive medicine, including vaccination can potentially play a major role in preserving the health and independence of older adults. However, this potential of widespread vaccination is rarely realized. Here, we give a brief overview of the problem, discuss concrete obstacles and the potential for expanded vaccination programs to promote healthy aging. CONCLUSION: The increasing healthcare burden of infectious diseases expected in aging populations could, to a large extent, be reduced by achieving higher vaccination coverage among older adults. Vaccination can thus contribute to healthy aging, alongside healthy diet and physical exercise. The available evidence indicates that dedicated programs can achieve substantial improvements in vaccination coverage among older adults, but more research is required to assess the generalizability of the results achieved by specific interventions (see Additional file 1).

Adjuvant system AS01: helping to overcome the challenges of modern vaccines.

INTRODUCTION: Adjuvants are used to improve vaccine immunogenicity and efficacy by enhancing antigen presentation to antigen-specific immune cells with the aim to confer long-term protection against targeted pathogens. Adjuvants have been used in vaccines for more than 90 years. Combinations of immunostimulatory molecules, such as in the Adjuvant System AS01, have opened the way to the development of new or improved vaccines. Areas covered: AS01 is a liposome-based vaccine adjuvant system containing two immunostimulants: 3-O-desacyl-4'-monophosphoryl lipid A (MPL) and the saponin QS-21. Here we describe studies investigating the mode of action of AS01, and consider the role of AS01 in enhancing specific immune responses to the antigen for selected candidate vaccines targeting malaria and herpes zoster. The effects of AS01 are rapid and transient, being localized to the injected muscle and draining lymph node. AS01 is efficient at promoting CD4+ T cell-mediated immune responses and is an appropriate candidate adjuvant for inclusion in vaccines targeting viruses or intracellular pathogens. Expert commentary: AS01 activity to enhance adaptive responses depends on synergistic activities of QS-21 and MPL. AS01 adjuvantation shows good prospects for use in new vaccines targeted to populations with challenging immune statuses and against diseases caused by complex pathogens.

From discovery to licensure, the Adjuvant System story.

Adjuvants are substances added to vaccines to improve their immunogenicity. Used for more than 80 years, aluminum, the first adjuvant in human vaccines, proved insufficient to develop vaccines that could protect against new challenging pathogens such as HIV and malaria. New adjuvants and new combinations of adjuvants (Adjuvant Systems) have opened the door to the delivery of improved and new vaccines against re-emerging and difficult pathogens. Adjuvant Systems concept started through serendipity. The access to new developments in technology, microbiology and immunology have been instrumental for the dicephering of what they do and how they do it. This knowledge opens the door to more rational vaccine design with implications for developing new and better vaccines.

Vaccine safety evaluation: Practical aspects in assessing benefits and risks.

Vaccines are different from most medicines in that they are administered to large and mostly healthy populations including infants and children, so there is a low tolerance for potential risks or side-effects. In addition, the long-term benefits of immunisation in reducing or eliminating infectious diseases may induce complacency due to the absence of cases. However, as demonstrated in recent measles outbreaks in Europe and United States, reappearance of the disease occurs as soon as vaccine coverage falls. Unfounded vaccine scares such as those associating the combined measles-mumps-rubella vaccine with autism, and whole-cell pertussis vaccines with encephalopathy, can also have massive impacts, resulting in reduced vaccine uptake and disease resurgence. The safety assessment of vaccines is exhaustive and continuous; beginning with non-clinical evaluation of their individual components in terms of purity, stability and sterility, continuing throughout the clinical development phase and entire duration of use of the vaccine; including post-approval. The breadth and depth of safety assessments conducted at multiple levels by a range of independent organizations increases confidence in the rigour with which any potential risks or side-effects are investigated and managed. Industry, regulatory agencies, academia, the medical community and the general public all play a role in monitoring vaccine safety. Within these stakeholder groups, the healthcare professional and vaccine provider have key roles in the prevention, identification, investigation and management of adverse events following immunisation (AEFI). Guidelines and algorithms aid in determining whether AEFI may have been caused by the vaccine, or whether it is coincidental to it. Healthcare providers are encouraged to rigorously investigate AEFIs and to report them via local reporting processes. The ultimate objective for all parties is to ensure vaccines have a favourable benefit-risk profile.

Vaccine Adjuvants: from 1920 to 2015 and Beyond.

The concept of stimulating the body's immune response is the basis underlying vaccination. Vaccines act by initiating the innate immune response and activating antigen presenting cells (APCs), thereby inducing a protective adaptive immune response to a pathogen antigen. Adjuvants are substances added to vaccines to enhance the immunogenicity of highly purified antigens that have insufficient immunostimulatory capabilities, and have been used in human vaccines for more than 90 years. While early adjuvants (aluminum, oil-in-water emulsions) were used empirically, rapidly increasing knowledge on how the immune system interacts with pathogens means that there is increased understanding of the role of adjuvants and how the formulation of modern vaccines can be better tailored towards the desired clinical benefit. Continuing safety evaluation of licensed vaccines containing adjuvants/adjuvant systems suggests that their individual benefit-risk profile remains favorable. Adjuvants contribute to the initiation of the innate immune response induced by antigens; exemplified by inflammatory responses at the injection site, with mostly localized and short-lived effects. Activated effectors (such as APCs) then move to draining lymph nodes where they direct the type, magnitude and quality of the adaptive immune response. Thus, the right match of antigens and adjuvants can potentiate downstream adaptive immune responses, enabling the development of new efficacious vaccines. Many infectious diseases of worldwide significance are not currently preventable by vaccination. Adjuvants are the most advanced new technology in the search for new vaccines against challenging pathogens and for vulnerable populations that respond poorly to traditional vaccines.

Safety assessment of adjuvanted vaccines: Methodological considerations.

Adjuvants mainly interact with the innate immune response and are used to enhance the quantity and quality of the downstream adaptive immune response to vaccine antigens. Establishing the safety of a new adjuvant-antigen combination is achieved through rigorous evaluation that begins in the laboratory, and that continues throughout the vaccine life-cycle. The strategy for the evaluation of safety pre-licensure is guided by the disease profile, vaccine indication, and target population, and it is also influenced by available regulatory guidelines. In order to allow meaningful interpretation of clinical data, clinical program methodology should be optimized and standardized, making best use of all available data sources. Post-licensure safety activities are directed by field experience accumulated pre- and post-licensure clinical trial data and spontaneous adverse event reports. Continued evolution of safety evaluation processes that keep pace with advances in vaccine technology and updated communication of the benefit-risk profile is necessary to maintain public confidence in vaccines.