Modeling The Economic Burden Of Adult Vaccine-Preventable Diseases In The United States

Maintaining Immunizations for Vaccine-Preventable Diseases in a Changing World

Immunization has saved an estimated 154 million lives over the past 50 years since the launch of the Essential (formerly Expanded) Program on Immunization in 1974, representing 6 lives saved every minute, every year, for 50 years. But achieving and maintaining high immunization coverage have required sustained political and public commitment, financial resources, strong partnerships, research and innovation, and communication and advocacy. New and evolving challenges to maintaining high immunization coverage have emerged alongside long-standing stubborn obstacles. We review some of these key challenges to immunization in this dynamic, changing world and summarize some promising solutions. Success in some regions of the world in eliminating polio, measles, and rubella, and reducing morbidity and mortality from other vaccine-preventable diseases, should provide hope that progress can be made in achieving and maintaining high immunization coverage. We cannot afford to do otherwise.

Cost-Effectiveness of the Pneumococcal Vaccine in the Adult Population: A Systematic Review

Objectives: Pneumococcal disease (PD), caused by S. pneumoniae, is a serious global health issue, primarily for adults over 65, due to its high mortality and morbidity rates. Recently, broader-serotype vaccines have been introduced to cope with tremendous hospital costs and decreasing quality of life. Our study aims to systematically review the cost-effectiveness of current PCVs (pneumococcal conjugate vaccines) and PPVs (pneumococcal polysaccharide vaccine) from 2018 to April 2024. Methods: Articles were identified through PubMed, Embase, and Cochrane. Key outcomes include an improved incremental cost-effectiveness ratio (ICER) and quality-adjusted life-years (QALY), with the article's quality assessed via the Consolidated Health Economic Evaluation Reporting Standards 2022 (CHEERS 2022). In total, 23 studies were included, with 22 studies of high quality and 1 of moderate quality. Results: These articles showed that PCV20 was the most cost-effective option compared with other vaccines, including PPV23, PCV13, PCV15, and PCV15/PPV23, for both young and older adults, regardless of risk factors. PCV20, when used alone, saved greater costs than PCV20, followed by PPV23. Conclusions: For countries applying lower-valency vaccines, switching to PCV20 as a single regimen would be the most beneficial for averting pneumococcal cases and reducing costs in adults aged 18-64 and over 65.

A risk science perspective on vaccines

Vaccines can be seen as one of the greatest successes in modern medicine. Good examples are the vaccines against smallpox, polio, and measles. Unfortunately, vaccines can have side effects, but the risks are considered by the health authorities and experts to be small compared to their benefits. Nevertheless, there are many who are skeptical of vaccination, something which has been very clearly demonstrated in relation to the COVID-19 disease. Risk is the key concept when evaluating a vaccine, in relation to both its ability to protect against the disease and its side effects. However, risk is a challenging concept to measure, which makes communication about vaccines' performance and side effects difficult. The present article aims at providing new insights into vaccine risks-the understanding, perception, communication, and handling of them-by adopting what is here referred to as a contemporary risk science perspective. This perspective clarifies the relationships between the risk concept and terms like uncertainty, knowledge, and probability. The skepticism toward vaccines is multifaceted, and influenced by concerns that extend beyond the effectiveness and safety of the vaccines. However, by clarifying the relationships between key concepts of risk, particularly how uncertainty affects risk and its characterization, we can improve our understanding of this issue.

Preventative care in student-run free clinics: a narrative review on feasibility, ethics, and recommendations

BACKGROUND

Student-run free clinics are critical for medical education and medical care of underserved populations. This paper explores the feasibility of establishing ethical preventative health services at student-run free clinics such as the Rochester Education and Advocacy for Community Health (REACH) Clinic, affiliated with the Mayo Clinic Alix School of Medicine. Our analysis discusses the challenges and ethical considerations of providing preventative healthcare in student-run clinics. This paper also provides recommendations for implementing preventative care at REACH and other student-run clinics.

METHODS

A literature search was conducted by an experienced librarian across four databases using keywords "student-run clinics" and "preventative healthcare." Additionally, contributing authors identified and gathered data about community service organizations that provide preventative healthcare services to residents of Rochester, MN and surrounding areas.

RESULTS

The literature search yielded 50 articles, 20 of which were included in the narrative review. Vaccinations and cancer screenings were the two preventative care initiatives most commonly undertaken by student-run clinics. The benefits of student-run clinic initiatives for both patients and students were an emerging theme. Clinics often achieved high vaccination and screening rates, and integration of preventative care topics into medical curricula was valued by students. However, the limitations of student-run clinics also emerged as a theme, particularly limitations to resources and comprehensive follow-up. 15 community health organizations in/around Rochester, MN were identified; of these, five provide preventative healthcare services.

CONCLUSION

Student-run clinics like REACH play a key role in delivering preventative care to underserved populations, bridging critical gaps in our healthcare system, and benefiting patients and students alike. However, the ethical principles of beneficence and non-maleficence should be considered when student-run clinics decide what services to offer. Preventative care has been successfully implemented at other student-run clinics but requires careful arrangement of adequate follow-up care, especially when it comes to cancer screening. Vaccinations are a low-cost, high-impact initiative that can be feasibly implemented at most student-run clinics.

A Clinical and Economic Comparison of Cell-Based Versus Recombinant Influenza Vaccines in Adults 18-64 Years in the United States

BACKGROUND

This analysis compares the cost-effectiveness of a cell-based influenza vaccine to a recombinant influenza vaccine, and each to no vaccination. The analysis is based on United States (US) commercial and societal perspectives.

METHODS

A Susceptible-Exposed-Infectious-Recovered (SEIR) transmission model of the total US population followed with a cost-effectiveness model for 18-64-year-olds was used to estimate the clinical and economic impact of vaccination over one influenza season (2018-2019). Deterministic and probabilistic sensitivity analyses were conducted.

RESULTS

Both enhanced vaccines prevented a substantial number of influenza cases and influenza-related deaths compared to no vaccination. The cell-based vaccine was associated with higher quality-adjusted life years (QALYs) gained compared to the recombinant vaccine or no vaccination. The cell-based vaccine had a 36% lower vaccination cost, amounting to $2.8 billion in cost savings, compared to the recombinant vaccine. The incremental cost-effectiveness ratios (ICERs) for the cell-based vaccine, compared to the recombinant vaccine or no vaccination, were dominant from all payer perspectives, regardless of risk groups.

CONCLUSIONS

Overall, the cell-based vaccine was cost-saving compared to the recombinant vaccine for subjects aged 18-64 years in the US, achieving comparable health outcomes with a significant reduction in associated costs.

The Annual Economic Burden of Respiratory Syncytial Virus in Adults in the United States

BACKGROUND

Current estimates of the economic burden of respiratory syncytial virus (RSV) are needed for policymakers to evaluate adult RSV vaccination strategies.

METHODS

A cost-of-illness model was developed to estimate the annual societal burden of RSV in US adults aged ≥60 years. Additional analyses were conducted to estimate the burden of hospitalized RSV in all adults aged 50-59 years and in adults aged 18-49 years with potential RSV risk factors.

RESULTS

Among US adults aged ≥60 years, the model estimated 4.0 million annual RSV cases (95% uncertainty interval [UI], 2.7-5.6 million) and an annual economic burden of $6.6 billion (95% UI, $3.1-$12.9 billion; direct medical costs, $2.9 billion; indirect costs, $3.7 billion). The 4% of RSV cases that were hospitalized contributed to 94% of direct medical costs. Additional analyses estimated $422 million in annual hospitalization costs among all adults aged 50-59 years. Among adults aged 18-49 years with RSV risk factors, annual per capita burden was highest among people with congestive heart failure at $51 100 per 1000 people.

DISCUSSION

The economic burden of RSV is substantial among adults aged ≥50 years and among adults aged 18-49 years with RSV risk factors, underscoring the need for preventive interventions for these populations.

State Medicaid Coverage and Reimbursement of Adult Vaccines Administered by Physicians and Pharmacists

Introduction

Effective from October 2023, federal law requires Medicaid programs to cover all recommended adult vaccines administered by physicians with no cost sharing for all eligibility groups. However, uniform coverage does not always translate to optimal uptake. Rather, other factors such as Medicaid reimbursement rates influence vaccine access and ultimately patient uptake. This study reviewed Medicaid policies to understand vaccine coverage and reimbursement, for both physicians and pharmacists, in all 50 U.S. states; Washington, DC; and Puerto Rico (collectively referred to as states).

Methods

Between March and September 2022, the researchers reviewed states' public Medicaid policies regarding adult vaccines, focusing on the service of injectable vaccine administration and 3 products: hepatitis A, 9-valent human papilloma virus, and 23-valent pneumococcal polysaccharide.

Results

Among 50 states with available data, 7 (14%) restricted Medicaid coverage for hepatitis A, 9-valent human papilloma virus, and/or 23-valent pneumococcal polysaccharide administered by physicians, and 15 (30%) did so for pharmacists. Median physician reimbursement rate was below the private sector rate for hepatitis A (89%) and 9-valent human papilloma virus (94%) but above the rate for 23-valent pneumococcal polysaccharide (108%). Median physician reimbursement for vaccine administration during an office visit was $11.86; the median pharmacist administration fee was $10.67.

Conclusions

Although federal law now requires all state Medicaid programs to cover, without cost sharing, all recommended adult vaccines administered by physicians, equitable vaccine access may be hindered by state coverage restrictions for pharmacists and by relatively low reimbursement rates relative to Medicare and commercial coverage for both physicians and pharmacists.

The Burden of Hepatitis A Outbreaks in the United States: Health Outcomes, Economic Costs, and Management Strategies

BACKGROUND

Hepatitis A (HepA) vaccines are recommended for US adults at risk of HepA. Ongoing United States (US) HepA outbreaks since 2016 have primarily spread person-to-person, especially among at-risk groups. We investigated the health outcomes, economic burden, and outbreak management considerations associated with HepA outbreaks from 2016 onwards.

METHODS

A systematic literature review was conducted to assess HepA outbreak-associated health outcomes, health care resource utilization (HCRU), and economic burden. A targeted literature review evaluated HepA outbreak management considerations.

RESULTS

Across 33 studies reporting on HepA outbreak-associated health outcomes/HCRU, frequently reported HepA-related morbidities included acute liver failure/injury (n = 6 studies of 33 studies) and liver transplantation (n = 5 of 33); reported case fatality rates ranged from 0% to 10.8%. Hospitalization rates reported in studies investigating person-to-person outbreaks ranged from 41.6% to 84.8%. Ten studies reported on outbreak-associated economic burden, with a national study reporting an average cost of over $16 000 per hospitalization. Thirty-four studies reported on outbreak management; challenges included difficulty reaching at-risk groups and vaccination distrust. Successes included targeted interventions and increasing public awareness.

CONCLUSIONS

This review indicates a considerable clinical and economic burden of ongoing US HepA outbreaks. Targeted prevention strategies and increased public awareness and vaccination coverage are needed to reduce HepA burden and prevent future outbreaks.

Influenza Vaccine Effectiveness Pre-pandemic Among Adults Hospitalized With Congestive Heart Failure or Chronic Obstructive Pulmonary Disease and Older Adults

BACKGROUND

Data are limited on influenza vaccine effectiveness (VE) in the prevention of influenza-related hospitalizations in older adults and those with underlying high-risk comorbidities.

METHODS

We conducted a prospective, test-negative, case-control study at 2 US hospitals from October 2018-March 2020 among adults aged ≥50 years hospitalized with acute respiratory illnesses (ARIs) and adults ≥18 years admitted with congestive heart failure (CHF) or chronic obstructive pulmonary disease (COPD) exacerbations. Adults were eligible if they resided in 1 of 8 counties in metropolitan Atlanta, Georgia. Nasopharyngeal and oropharyngeal swabs were tested using BioFire FilmArray (bioMérieux, Inc.) respiratory panel, and standard-of-care molecular results were included when available. Influenza vaccination history was determined from the Georgia vaccine registry and medical records. We used multivariable logistic regression to control for potential confounders and to determine 95% confidence intervals (CIs).

RESULTS

Among 3090 eligible adults, 1562 (50.6%) were enrolled. Of the 1515 with influenza vaccination history available, 701 (46.2%) had received vaccination during that season. Influenza was identified in 37 (5.3%) vaccinated versus 78 (9.6%) unvaccinated participants. After adjustment for age, race/ethnicity, immunosuppression, month, and season, pooled VE for any influenza-related hospitalization in the eligible study population was 63.1% (95% CI, 43.8-75.8%). Adjusted VE against influenza-related hospitalization for ARI in adults ≥50 years was 55.9% (29.9-72.3%) and adjusted VE against influenza-related CHF/COPD exacerbation in adults ≥18 years was 80.3% (36.3-93.9%).

CONCLUSIONS

Influenza vaccination was effective in preventing influenza-related hospitalizations in adults aged ≥50 years and those with CHF/COPD exacerbations during the 2018-2020 seasons.

Attitudes and practices to adult vaccination among physicians before and after COVID-19 pandemic in the United Arab Emirates

Introduction

Vaccination remains underutilised worldwide with low vaccine uptake rates across the board with many adults remaining unprotected. Across the Arab world, attitudes towards vaccines vary but high rates of vaccine hesitancy have been found. This study aims to explore the adult vaccination attitudes and practices by physicians in the UAE, both before and after the introduction of the COVID-19 vaccines.

Methodology

This cross-sectional, descriptive study used convenience and snowball sampling to collect comprehensive data from UAE physicians. A self-administered questionnaire was distributed in two stages: the first (pre-COVID-19 vaccines) between the months of June and October 2020 and the second between the months of November 2022 and March 2023.

Results

1000 responses, 500 from each time period, were collected. Nearly a third were family physicians or internists with more than 70% of the physicians working in governmental hospitals. 95% agreed that vaccines are safe in both cohorts but 74.4% reported not having enough time to advise about vaccines. 80.8% of physicians in the 2022 cohort reported safety concerns as the most common reason for patients to refuse vaccines. The most recommended vaccines were influenza (68.6%), Hepatitis B (66.0%) and HPV (61.4%), with pneumococcal coming in close at 57.8%. Family medicine physicians showed the highest utilisation of preventive practices across both cohorts. Nearly half of all family medicine physicians did not regularly evaluate both the influenza and general immunisation status of their patients. 54.6% of physicians reported having patients with VPDs in the last five years (not including COVID-19) in 2022.

Conclusion

Physicians have overly positive attitudes, but their practices reflect a more superficial appreciation of vaccines and lack of initiative. Physicians need to adopt a pro-vaccine stance, armed with the proper tools and the right mentality and beliefs.

Cost of illness of the vaccine-preventable diseases influenza, herpes zoster and pneumococcal disease in France

BACKGROUND

The incidence of certain vaccine-preventative diseases, such as influenza, herpes zoster and pneumococcal infection, continues to be high despite the availability of vaccines, resulting in a substantial health and economic burden on society, particularly among older adults aged ≥65 years.

METHODS

A cost calculator was developed to assess the cost of illness of influenza, herpes zoster and pneumococcal disease in France. Direct medical costs related to diagnosis and treatment in the older adult population in both inpatient and outpatient settings were modelled over a 1-year time horizon. Scenario analyses were conducted to determine the impact of hospitalizations on the results by considering only influenza-attributed diagnoses.

RESULTS

In France, influenza has the highest incidence, followed by herpes zoster and pneumococcal disease. Similarly, influenza poses the greatest cost burden among all older adults, while pneumococcal disease poses the greatest cost burden among those aged 65-74 years. When considering only influenza-attributed diagnoses, the number of inpatient visits and associated costs was reduced by 63% in the overall older adult population. In the low-incidence season, the number of inpatient visits and associated costs were reduced by 69%, while in the high-incidence season, the number of inpatient visits and associated costs increased by 63%.

CONCLUSION

Influenza remains a leading vaccine-preventable disease among older adults in France, resulting in a substantial economic burden that could be prevented by increasing vaccine uptake.

Implementing Effective Care in a University Population Based on National Vaccination Recommendations

Vaccines are among the most cost-effective and successful medical interventions, saving approximately 2.3 million lives annually. Unfortunately, vaccination coverage for adults remains low, leading to unnecessary and costly health consequences. An initial chart review revealed that 95% (N = 20) of students were not up to date with vaccines. In a patient survey, 100% of students (N = 21) did not recall receiving useful vaccine information, but 66.7% reported it would be helpful (≥4 of 5 on the Likert scale). Strategies supporting effective care, an Institute of Medicine quality domain, were used to address these gaps. The aim was to increase effective care in university adult students for vaccines by 30% over 90 days. The quality improvement method of Plan-Do-Study-Act cycles was used to evaluate iterative tests of change. Examining contextual elements, team and patient feedback, aggregate data, and run charts informed tests of change over 4 cycles. Core interventions included enhanced screening, vaccine shared decision-making, provider checklists, and a team engagement plan. Greater than 83% (N = 152) of students were not up to date with vaccines as per national guidelines. Over 8 weeks, the team effectively referred students for 265 of the 274 vaccines they were eligible for-an accuracy rate of 95.3%. The aim score, a mean composite score reflecting all 3 interventions, increased from 49% to 95%. Effective care for vaccine uptake increased by 83.8%-far exceeding the goal. Campus health centers and other primary care settings could benefit from adopting a similar strategy that provides clear benefits to patients and the broader community while decreasing health care costs.

Reduced mortality, complications, and economic burden among medicare beneficiaries receiving influenza antivirals

INTRODUCTION

Antiviral therapy may be underutilized in patients at high risk for increased clinical and economic burden (e.g. older adults). We aimed to examine the benefits associated with antiviral treatment of seasonal influenza among treated and untreated Medicare beneficiaries.

METHODS

This retrospective study of Medicare Claims Research Identifiable Files identified patients ≥66 years old with an influenza diagnosis in outpatient setting between October 2016-March 2019 (flu seasons 2016-2018). Index date defined as date of first claim with influenza diagnosis; baseline as the 12 months pre-index. Treated patients received antivirals ≤2 days from index. Untreated patients had no antivirals ≤6 months post-index. Treated/untreated patients were 1:1 propensity score matched. Outcomes (death, all-cause and respiratory-related healthcare resource utilization [HCRU] and costs) were assessed until death or up to 6 months post-index. Descriptive statistics were reported; Kaplan-Meier estimation was used for survival over time.

RESULTS

Among 116,901 matched patient pairs, all-cause mortality within 6 months from index diagnosis was 1.6% among treated versus 4.3% among untreated patients. Rates (treated versus untreated) of all-cause inpatient hospitalizations during follow-up were 13.9% versus 22.7% and respiratory-related hospitalizations were 4.2% versus 9.0%. Mean (SD) total all-cause and respiratory-related costs were $9,830 ($18,616.0) and $900 ($4016.4) among the treated, respectively, versus $13,207 ($24,405.1) and $2,024 ($7,623.7) among untreated, respectively. All differences were statistically significant (p < 0.001).

CONCLUSIONS

Lack of antiviral treatment is associated with increased mortality, HCRU, and economic burden in older Medicare beneficiaries with seasonal influenza. Future research should investigate whether the choice of antivirals affects influenza burden.

Regional factors associated with pneumococcal vaccination coverage among U.S. adults with underlying chronic or immunocompromising conditions

The Centers for Disease Control recommends pneumococcal vaccination for U.S. adults aged 19-64 years with chronic or immunocompromising conditions, however, vaccination coverage is low and regional variations in coverage are rarely studied. This study examined pneumococcal vaccination coverage at the metropolitan statistical area (MSAs) level and identified regional factors associated with pneumococcal vaccination using the combined IBM® Watson Health MarketScan® Commercial and Medicare Supplemental databases. Pneumococcal vaccination coverage, clinical and socioeconomic factors were calculated for each MSA. Ordinary least square and spatial regression models were used to examine factors associated with vaccination. Results indicated that the national pneumococcal vaccination coverage was 13.4% with a large variation across MSAs (0-34%). The spatial error model, model with the best fit, showed that proportions of the population who were ≥50 years of age, received an influenza vaccine, or had health maintenance organization health plans were positively associated with pneumococcal vaccination coverage. In summary, we found that national pneumococcal vaccination coverage was low and there was substantial variation across MSAs. Regional factors identified may help inform interventions to improve pneumococcal vaccination coverage across geographies.

Flu Shots Unveiled: A Global Systematic Review of Healthcare Providers' Uptake of, Perceptions, and Attitudes toward Influenza Vaccination

BACKGROUND AND PURPOSE

Influenza, with its potential for widespread transmission and significant health repercussions for individuals and populations, demands the immediate implementation of effective preventive measures. Vaccination stands as a long-standing evidence-based strategic approach to bolster immunity, especially for healthcare providers at heightened risk due to repeated exposure. Nevertheless, studies indicate a variance in adherence to recommended vaccination protocols and a notable prevalence of hesitancy and negative attitudes toward influenza vaccination among this critical group globally. Recognizing the multifaceted nature of attitudes is essential for the development of targeted interventions and strategies tailored to address the specific concerns and motivations of healthcare providers. To this end, this study synthesized the evidence gathered from an exhaustive systematic review of studies on healthcare providers' uptake of and perceptions and attitudes toward influenza vaccination.

METHODS

A systematic literature search was conducted across the databases PubMed, CINAHL, PsycINFO, Scopus, Web of Science, and EMBASE. The review adhered to PRISMA guidelines, using Covidence for screening. The process involved 4970 references, with 2684 screened after duplicate removals and 1891 excluded, leaving 793 full texts evaluated, resulting in a final 368 selected references for analysis. Due to the considerable heterogeneity observed among the studies, a narrative synthesis method was employed.

RESULTS

Five themes emerged from the systematic review's analysis, offering a multifaceted perspective on healthcare providers' attitudes toward influenza vaccination: (1) fostering positive views: factors promoting attitudes toward influenza vaccines; (2) navigating hesitancy: barriers and challenges to attitudes on influenza vaccines; (3) empowering change: interventions and their impact on healthcare providers' attitudes; (4) pandemic overlap: intersecting attitudes toward influenza and COVID-19 vaccines; and (5) twin challenges: the impact of mandatory policy on attitudes and influenza vaccination.

CONCLUSIONS

Healthcare providers' attitudes toward influenza vaccination are complex and influenced by intrinsic and extrinsic motivations, barriers, demographics, organizational factors, interventions, pandemic contexts, and policy considerations. Effective strategies for promoting influenza vaccination should be multifaceted, adaptable, and tailored to address these interconnected aspects, ultimately contributing to improved vaccination rates and public health outcomes.

Epidemiology of influenza over a ten-year period in Belgium: overview of the historical and current evidence

BACKGROUND

Generally influenza, a contagious respiratory disease, leads to mild illness, but can present as a severe illness with significant complications for some. It entails significant health challenges and an economic burden. Annual vaccination is considered the most effective preventive measure against influenza, especially in high-risk groups.

METHOD

Epidemiological, demographic and vaccination data of influenza from 2009-to-2019 is collected from Sciensano, the Belgian Institute for Health. Sciensano monitors influenza virus through two surveillances: the Influenza-Like Illness (ILI) surveillance in primary care and the Severe Acute Respiratory Infections (SARI) surveillance in hospital settings.

RESULTS

49.6% [± 8.5] of all ILI-samples tested positive in this period. Influenza A was the dominant circulating type, accounting for 73.7% [± 27.5] of positive samples, while influenza B accounted for 24.3% [± 26.7]. For SARI-surveillance, the average rate of samples tested positive was 36.3% [± 9.3]. Influenza A was responsible for respectively 77.7% [± 23.8] of positive samples and influenza B for 22.2% [± 23.7]. Since 2010, epidemics typically lasted about 9.3 weeks [± 2.7]. From 2012 to 2019 the average vaccine effectiveness was 34.9% [± 15.3].

CONCLUSION

Influenza is quickly considered a trivial disease, but can have substantial repercussions. It remains difficult to identify the level of treat of influenza due to antigenic evolution. Measures to prevent, control and treat are needed. Vaccines that provide broader and more durable protection that can be produced more rapidly could be a potential solution.

Childhood Vaccination Practices and Parental Hesitancy Barriers in Rural and Urban Primary Care Settings

The purpose of our study was to identify primary care providers' (PCPs') practices in promoting childhood vaccination and their perceptions regarding barriers to vaccination in a primarily rural state. In January-May 2022, we conducted a mail and online survey of PCPs across Montana (n = 829). The survey included modules on routine immunizations in children 0-2 years old and COVID-19 vaccination in children 5-17 years old. The survey response rate was 36% (298/829). We categorized PCPs as working in rural (n = 218) or urban areas (n = 80), based on Rural-Urban Commuting Area codes. We then compared responses between rural and urban PCPs using chi-square tests. Urban PCPs (90-94%, depending on vaccine) stocked routinely recommended vaccines more frequently than rural PCPs (71-84%), but stocked the COVID-19 vaccine less often than rural PCPs (44% vs. 71%, respectively, p < 0.001). A higher percentage of rural providers reported parental beliefs that vaccine-preventable diseases are not severe enough to warrant vaccination (48% vs. 31%, p = 0.01) and concerns that vaccination will weaken their child's immune system (29% vs. 6%, p < 0.001). More rural (74%) compared to urban (59%) PCPs identified a social media campaign from local health departments promoting early childhood vaccinations as an effective strategy to increase childhood vaccination rates (p = 0.01). We identified key differences in some childhood vaccination practices and barriers between rural and urban PCPs. Interventions to increase rural vaccination rates could include increasing the number of providers stocking all recommended vaccines, identifying strategies to address parents' concerns regarding vaccine necessity, and collaborations with public health departments.

Addressing racial inequality and its effects on vaccination rate: A trial comparing a pharmacist and peer educational program (MOTIVATE) in diverse older adults

BACKGROUND: The mortality, morbidity, health care utilization, and cost attributable to vaccine-preventable diseases are substantial for those aged 50 years and older. Although vaccination is the most cost-effective strategy to prevent common infectious diseases in older adults, vaccination rates remain below US Centers for Disease Control and Prevention benchmarks, especially among racial minorities. Historical mistrust, structural racism within the US medical system, and misinformation contributed to lower immunization rates among minorities, especially Black Americans. To address the critical need to increase knowledge and trust in vaccination, 2 community-based educational interventions were tested: a pharmacist-led didactic session (PHARM) and a peer-led educational workshop (PEER). OBJECTIVE: To determine and compare the effectiveness and costs of PEER and PHARM community-based education models in improving knowledge and trust in vaccinations. METHODS: The Motivating Older adults to Trust Information about Vaccines And Their Effects (MOTIVATE) study was a cluster-randomized trial conducted in the greater Delaware Valley Region sites from 2017 to 2020. The included sites (7 senior centers, 3 housing units, 1 church, and 1 neighborhood family center) predominantly served Black communities. Participants were randomized to either PHARM or PEER sessions covering influenza, pneumococcal disease, herpes zoster, and beliefs related to vaccines. Peer leaders facilitated smaller workshops (5-10 participants), whereas pharmacists conducted larger didactic lectures with 15-43 participants. Outcomes were captured through a self-administered survey at baseline, postprogram, and 1 month after the program. Intervention costs were measured in 2017 US dollars. RESULTS: 287 participants were included. Their mean age was 74.5 years (SD = 8.94), 80.5% were women, 64.2% were Black, and 48.1% completed some college. Knowledge scores within groups for all 3 diseases significantly increased postprogram for both PEER and PHARM and were sustained at 1 month. Between-group knowledge differences were significant only for influenza (PEER participants had significantly larger improvement vs PHARM). Vaccination trust significantly increased in both groups. Total program costs were $11,411 for PEER and $5,104 for PHARM. CONCLUSIONS: Both interventions significantly improved knowledge and trust toward vaccination and retained their effect 1 month after the program. The 2 effective community-based education models should be expanded to ensure timely and trusted information is available to educate older adults about vaccine-preventable diseases. Further research is encouraged to assess the long-term cost-effectiveness of these models' utilization on a larger scale. DISCLOSURES: Dr Schafer is an employee of Merck; however, at the time of the project, he was a professor at Thomas Jefferson University. The other authors have no conflicts of interest to disclose. This study was supported in part by a research grant from the Investigator-Initiated Studies Program of Merck Sharp & Dohme Corp. The opinions expressed in this article are those of the authors and do not necessarily represent those of Merck Sharp & Dohme Corp. The sponsor played no role in the design and conduct of the study; in the collection, analysis, and interpretation of the data; or in the preparation, review, or approval of the article. Study Registration Number: NCT03239665.

The burden of influenza and the role of influenza vaccination in adults aged 50-64 years: A summary of available evidence

Influenza is a vaccine-preventable disease and a global public health problem. Although most national influenza vaccination recommendations focus on subjects aged ≥65 years, an extensive burden of influenza has also been reported in those aged ≥50 years and is exacerbated by immune system aging. The main purpose of this review is to provide an overview of the burden of influenza and its potential prevention within the 50-64 age-group. These subjects account for a large proportion of the workforce, and play a central economic and social role. Individuals aged 50-64 years had a 3-times higher rate of hospitalization and a 9-fold higher mortality rate attributable to influenza than those aged 18-49-years, generating higher influenza-related hospitalization costs. Available data suggest that including healthy subjects aged 50-64 years in influenza vaccination recommendations would allow a broader population to be reached, reducing the economic and social burden of influenza.

Challenges of vaccination information system implementation: A systematic literature review

Globally, healthcare services have begun to show interest in switching from paper-based to electronic-based vaccination records through Vaccination Information Systems (VIS). VIS have been implemented in various countries, but the study on the challenges of implementing VIS in these countries is still limited. The challenges of implementing VIS need to be understood to become a subject of discussion and anticipation by other countries that are just starting to implement VIS. We analyzed 32 selected publications from 634 initially retrieved. Fourteen challenges were successfully identified when implementing VIS, including interoperability, data quality, security and privacy, standardization, usability, internet connectivity, infrastructure, workflow, funding, government regulations, awareness, skeptical response, computer literacy, and staff-related challenges. The challenges of interoperability and data quality were found to be the most widely discussed by previous studies. In addition to identifying the challenges, this study includes a series of solutions that can be applied to overcome each challenge.

Use of Information and Communication Technology Strategies to Increase Vaccination Coverage in Older Adults: A Systematic Review

BACKGROUND

Coverage rates of routinely recommended vaccines in older adults still fall below the targets established by international and national advisory committees. As a result, related diseases still have a high incidence, morbidity, and mortality. Information and Communication Technologies (ICT) could provide useful tools to improve immunization rates by bringing information directly to the target user at a relatively low cost. The present research aims to systematically review recent literature on interventions applying ICT to improve the uptake of influenza, pneumococcal, COVID-19 and herpes zoster immunization rates among older adults.

METHODS

Studies published in English between 1 January 2000 and 10 November 2022 were identified by searching electronic medical databases (PubMed, Scopus) and were independently reviewed by two different authors. A total of 22 studies were included in this review.

FINDINGS

Interventions applied the following ICT tools: phone calls, text messages, messages sent via personal electronic medical records, automated phone calls, remote patient monitoring in a home telehealth program and emails. In terms of the vaccines promoted, 11 studies prompted the influenza vaccine, four prompted the influenza and pneumococcal vaccines, three the pneumococcal vaccine, two the herpes zoster vaccine, one the COVID-19 vaccine and one both the pneumococcal and herpes zoster vaccines. Overall, more than half of the studies (n = 12) found some level of effectiveness of these ICT strategies in increasing vaccination rates among older adults, while five studies were partially effective (for specific vaccines or population subgroups), and five reported no significant effect.

CONCLUSIONS

Prevention programs using ICT tools could be effective in promoting immunizations among older adults.

Cost-Effectiveness Analyses of Digital Health Technology for Improving the Uptake of Vaccination Programs: Systematic Review

BACKGROUND

Vaccination is the most effective strategy to prevent infectious diseases, yet vaccination coverage has not reached the target level. To promote vaccination uptake, digital health interventions (DHIs) have been used in various vaccination programs.

OBJECTIVE

This study aimed to perform a systematic review of the cost-effectiveness analyses of DHIs for the improvement of the uptake of vaccination programs.

METHODS

A literature review was conducted in MEDLINE (Ovid), Embase (Ovid), APA PsycINFO (Ovid), Web of Science, Scopus, CINAHL Ultimate (EBSCOhost), Center for Review and Dissemination, and Institute for IEEE Xplore up to October 2022. Health economic evaluations that met the following inclusion criteria were included: (1) adult or pediatric vaccination programs; (2) interventions delivered through digital technology; (3) full-scale health economic analyses including cost-effectiveness, cost-utility, cost-benefit, or cost-consequence analyses; and (4) evaluations conducted by model-based or trial-based analyses. The quality of each included study was evaluated using the Consolidated Health Economic Evaluation Reporting Standards (CHEERS).

RESULTS

The systematic review included 7 studies. Four of the cost-effectiveness studies were conducted by model-based analyses, and 3 were trial-based analyses. One study reported the additional cost per quality-adjusted life years (QALYs) gained, whereas 6 studies reported the additional cost per individual vaccinated (or return case). The vaccines targeted the human papillomavirus (HPV) vaccine, influenza vaccination, measles-mumps-rubella (MMR) vaccine, and children immunization at different ages. The DHIs were delivered by television campaign, web-based decision aid, SMS text message, telephone, and computer-generated recall letters. The studies were classified as very good (n=5) and good (n=2) qualities. One study concluded that the DHI was cost-saving, and 6 studies concluded that the DHI was cost-effective.

CONCLUSIONS

This study is the first systematic review on cost-effectiveness analyses of DHIs to improve vaccination uptake. All included studies have good to very good quality on study assessment and reported the DHIs to be cost-saving or cost-effective in the improvement of vaccination uptake.

Carriage prevalence, serotype distribution, antimicrobial resistance, pspA typing and pilus islets of Streptococcus pneumoniae isolated from adults living in a Brazilian urban slum

INTRODUCTION

For Brazilian adults, pneumococcal vaccines have been usually taken only by those who are at higher risk for development of pneumococcal diseases. Since populations from lower socioeconomic status are at high risk of acquiring pneumococcal infections, we investigated the carriage prevalence, colonization risk factors, capsular and surface protein types, and antimicrobial resistance among pneumococcal isolates recovered from adults living in a Brazilian urban slum.

METHODS

Between September-December 2016, we conducted a cross-sectional study among individuals aged ≥ 18 years who attended a public primary clinic in Niterói/RJ, Brazil. Pneumococci were isolated by culture on sheep blood agar plates with and without gentamicin. Antimicrobial susceptibility was determined for all isolates. We used PCR to determine capsular types, PspA families (Fam) and pilus islets (PI).

RESULTS

Of 385 adults, 32 (8.3 %) were pneumococcal carriers. Three carriers had two different pneumococci, totaling 35 isolates. After multivariate analysis, smoking, previous hospitalization, alcohol consumption and co-habitation with children aged < 6 years increased the odds of pneumococcal carriage, but antibiotic use in the previous 2 weeks was found to be a protective factor. Fourteen different serogroups/serotypes were detected and the prevalent ones were 9 N/L, 10A, 15B/C and 35F/47F (n = 3; 8.6 % each). Non-typeable (NT) isolates made up 31.4 %. All isolates were susceptible to chloramphenicol, levofloxacin and vancomycin. We found eight (22.9 %) penicillin non-susceptible pneumococci (PNSP) with minimum inhibitory concentrations (MICs) of 0.38-1.5 μg/mL. The two (5.7 %) erythromycin-resistant isolates had MIC > 256 μg/mL, cMLS_B phenotype and the erm(B) gene. Twelve (34.3 %) and 17 (48.6 %) isolates had PspA Fam1 and Fam2, respectively. Three (8.6 %) isolates had genes for pilitwo PI-1 and one PI-2.

CONCLUSION

We detected a low frequency of pneumococcal carriage among the adult population, but a high diversity of serotypes. Frequencies of PNSP and NT isolates resistant to antimicrobial agents are concerning.

Adult immunization practices, challenges and opportunities in Central America and the Caribbean: Advisory board proceedings

As individuals age, they become increasingly prone to infectious diseases, many of which are vaccine-preventable diseases (VPDs). Adult immunization has become a public health priority in the modern era, yet VPDs vaccination rates for adults are low worldwide. In Central America and Caribbean, national recommendations and vaccination practices in adults differ across countries, and adult vaccination coverage data are limited. An advisory board comprised infectious disease experts, pulmonologists, geriatricians, occupational health, and public health professionals for Central America and Dominican Republic was convened to: a) describe adult immunization practices in these countries; b) discuss challenges and barriers to adult vaccination; and c) find strategies to increase awareness about VPDs. The advisory board discussions reflect that national immunization guidelines typically do not include routine vaccine recommendations for all adults, but rather focus on those with risk factors. This is the case for influenza, pneumococcal, and hepatitis B immunizations. Overall, knowledge lacks about the VPD burden among health-care professionals and the general public. Even more, there is insufficient information on vaccinology for students in medical schools. Actions from the responsible authorities - medical schools and scientific societies which can advocate for vaccination and a better knowledge in vaccinology - can help address these issues. A preventive medicine culture in the workplace may contribute to the advancement of public opinion on vaccination. Promoting vaccine education and research could be facilitated via working groups formed by disease experts, public and private sectors, and supranational authorities, in an ethical and transparent manner.

Associations between pharmacy choice and influenza vaccination: Mail order vs community pharmacy users

BACKGROUND: Despite the effectiveness of vaccines, US adult vaccination rates remain low. This is especially true for the influenza vaccine, which is recommended annually and widely available. The accessibility of community pharmacies as convenient places to receive influenza vaccines has been shown to increase uptake. However, use of mail order pharmacies may reduce in-person pharmacist encounters and reduce the likelihood that users receive annual influenza vaccines. OBJECTIVE: To determine the association between the type of pharmacy a patient uses and their likelihood of receiving an influenza vaccine. METHODS: This cross-sectional cohort study used the 2018 Medical Expenditure Panel Survey to observe noninstitutionalized US adult pharmacy users. Pharmacy type was dichotomized into community use only vs any mail order pharmacy use. Multivariable weighted logistic regression was used to identify associations between the type of pharmacy used and influenza vaccination, adjusting for sociodemographic, health status, and health care access and utilization confounders. All analyses were stratified by age (< 65 and ≥ 65 years). RESULTS: The aged younger than 65 years and aged 65 years and older samples had 8,074 and 4,037 respondents who represented 95,930,349 and 40,163,276 weighted observations, respectively. Compared with community pharmacy users, mail order users were more likely to be aged 65 and older, be White, have high income, and have a usual source of care (P < 0.0001). Adjusted odds ratios (AORs) for influenza vaccination were significantly lower among community pharmacy users than mail order users among individuals aged younger than 65 years (AOR=0.71; 95% CI = 0.580.87) but was not significant among those aged 65 years and older (AOR = 0.87; 95% CI = 0.69-1.09). CONCLUSIONS: Community pharmacy users aged younger than 65 years are less likely to receive the influenza vaccine than their mail order pharmacy user counterparts. These counterintuitive results could be caused by residual confounding due to differences in factors that influence pharmacy use type and vaccination likelihood. Further exploration is needed to account for differences between these populations that independently drive vaccination choice. DISCLOSURES: Dr Burbage was a fellow in the Real World Evidence, Population Health and Quality Research Postdoctoral Fellowship Program in collaboration with University of North Carolina Eshelman School of Pharmacy and Pharmacy Quality Alliance, and supported by Janssen Scientific Affairs at the time of this study. She is now employed by Janssen Scientific Affairs. Dr Parikh is an employee of Pharmacy Quality Alliance. Dr Campbell was employed by Pharmacy Quality Alliance at the time of the study. He is now employed by Merck Sharp & Dohme Corp., a subsidiary of Merck & Co., Inc., Kenilworth, NJ, USA. Dr Ramachandran has received an unrelated research contract with Pharmacy Quality Alliance. Dr Gatwood has received vaccine-related research grants from Merck & Co. and GlaxoSmithKline unrelated to this project and consulting fees for a vaccine-related expert panel with Merck & Co. unrelated to this manuscript and is an advisory board member with Janssen Scientific Affairs. Dr. Urick was employed by the UNC Eshelman School of Pharmacy at the time of this writing and is currently employed by Prime Therapeutics. He has received community pharmacy-related consulting fees from Cardinal Health and Pharmacy Quality Solutions unrelated to this work. Dr Ozawa has a research grant from Merck & Co. unrelated to this project. This project did not receive funding from any agency in the public, commercial, or not-for-profit sectors.

Improving older adults' vaccination uptake: Are existing measures of vaccine hesitancy valid and reliable for older people?

We sought to establish whether two recently developed measures, the 5C scale and the Vaccination Attitudes Examination (VAX) were reliable and valid for use with older adults. A total of 372 UK-dwelling participants (65-92 years, M = 70.5 years, SD = 4.6) completed a cross-sectional survey measuring health and socio-demographic characteristics in relation to vaccine uptake for influenza, pneumococcal and shingles. The 5C and VAX scales were administered to test their reliability, validity and dimensionality. Both scales showed good internal reliability and convergent, discriminant and concurrent validity. Their factor structures were also confirmed, supporting their use with older adult populations.

The Awareness and Attitude of Physicians to Older Adult Routine Vaccination Scheme

PURPOSE

Immunization is one of the main components of preventive medicine measures. Influenza, pneumococcal, tetanus, and shingles vaccines are recommended for older adults routinely. This study aimed to show the knowledge and attitudes of the physicians to older adults' vaccination schemes.

PATIENTS AND METHODS

An electronic self-reported questionnaire was sent to physicians between March and July 2021 in Turkey. Sociodemographic characteristics, professional experience, area of expertise, and practice setting of the participants were recorded. As multiple-choice questions; the routinely recommended vaccines, and vaccines suggested in their daily practice before and after the COVID-19 pandemic were enquired.

RESULTS

A total of 435 participants were included in the study. 43.9% of the patients were primary family physicians, and 36.8% were internists. 63.4% of the participants had reported reviewing the National Vaccination Scheme. 94.5% of the medical doctors indicated that they had recommended any vaccination to their patients. 20.9% of the practitioners could select four or five of the routinely recommended vaccines. Reviewing the National Adult Vaccination Scheme and being an internist were positively related to predicting the recommended vaccines. The recommendation rates of influenza and pneumococcal conjugate (PCV13) were seen at 88% and 78%, respectively. Except for PCV13, recommendation rates of other routine vaccines were decreased after the pandemic.

CONCLUSION

Awareness of routine vaccination schedules should be improved among health-care professionals, and reminders for immunization should be provided periodically in each health-care setting.

Vaccinations Status against Vaccine-Preventable Diseases and Willingness to Be Vaccinated in an Italian Sample of Frail Subjects

BACKGROUND

Study aim was to investigate the vaccination status against vaccine-preventable diseases (VPD) of frail adults during the SARS-CoV-2 pandemic and, for those subjects eligible for at least one vaccine, with respect to the recommended vaccination in line with the Italian National Vaccination Prevention Plane (NPVP), to explore the willingness to be vaccinated.

METHODS

A cross-sectional study was carried out among adults aged ≥ 60, immunocompromised or subjects affected by chronic conditions.

RESULTS

Among the 427 participants, a vaccination coverage rate lower than the targets for all the vaccines considered was found. Of those, 72.6% of subjects stated their willingness to receive recommended vaccinations, and 75.2% of the respondents stated that the advice to undergo vaccinations was received by the General Practitioner (GP). In a multivariable logistic regression model, higher odds of recommended VPD vaccination uptake (defined as having two or more of the recommended vaccinations) were associated with the willingness towards recommended VPD vaccination (Odds Ratio = 3.55, 95% Confidence Interval: 1.39 to 9.07), university education (OR = 2.03, 95% CI: 1.03 to 3.97), but having another person in the household (OR = 0.52, 95% CI: 0.28 to 0.97), and history of oncological disease (OR = 0.39, 95% CI: 0.18 to 0.87) were predictive of lower odds of vaccination uptake. In another multivariable model, higher odds of willingness to receive vaccines were associated with kidney disease (OR = 3.3, 95% CI: 1.01 to 10.5), perceived risk of VPD (OR = 1.9, 95% CI: 1.02 to 3.3), previous influenza vaccination (OR = 3.4, 95% CI: 1.8 to 6.5), and previous pneumococcal vaccination (OR = 3.1, 95% CI: 1.3 to 7.7), but increasing age (OR = 0.93 per year, 95% CI: 0.91 to 0.97), working (OR = 0.40, 95% CI: 0.20 to 0.78), and fear of vaccine side effects (OR = 0.38, 95% CI: 0.21 to 0.68) were predictive of lower odds of willingness to receive vaccines.

CONCLUSIONS

Despite specific recommendations, vaccination coverage rates are far below international targets for frail subjects. Reducing missed opportunities for vaccination could be a useful strategy to increase vaccination coverage in frail patients during the routine checks performed by GPs and specialists.

The Impact of Broader Value Elements on Cost-Effectiveness Analysis: Two Case Studies

OBJECTIVES

This study aimed to explore the impact of including broader value elements in cost-effectiveness analyses by presenting 2 case studies, one on human papillomavirus (HPV) infection and one on early-stage Hodgkin's lymphoma (ESHL).

METHODS

We identified broader value elements (eg, patient and caregiver time, spillover health effects, productivity) from the Second Panel's Impact Inventory and the ISPOR Special Task Force's value flower. We then evaluated the cost-effectiveness of HPV vaccination versus no vaccination (case 1) and combined modality therapy (CMT) versus chemotherapy alone for treatment of adult ESHL (case 2) using published simulation models. For each case study, we compared incremental cost-effectiveness ratios considering health sector impacts only (the "base-case" scenario) with incremental cost-effectiveness ratios incorporating broader value elements.

RESULTS

For vaccination of US girls against HPV before sexual debut versus no vaccination, the base-case result was $38 334 per disability-adjusted life-year averted. Including each broader value element made cost-effectiveness progressively more favorable, with HPV vaccination becoming cost-saving (ie, reducing costs and averting more disability-adjusted life-years) when the analysis incorporated productivity costs. For CMT versus chemotherapy alone in patients with ESHL, the base-case result indicated that CMT was cost-saving. Including all elements made this treatment's net monetary benefits (the sum of its averted resource costs and the net value of its health impacts) less favorable, even as the contribution from CMT's near-term health benefits grew.

CONCLUSIONS

Including broader value elements can substantially influence cost-effectiveness ratios, although the direction and the magnitude of their impact can differ across interventions and disease context.

Adjuvant Discovery via a High Throughput Screen using Human Primary Mononuclear Cells

Motivation

Vaccines are a key biomedical intervention to prevent the spread of infectious diseases, but their efficacy can be limited by insufficient immunogenicity and nonuniform reactogenic profiles. Adjuvants are molecules that potentiate vaccine responses by inducing innate immune activation. However, there are a limited number of adjuvants in approved vaccines, and current approaches for preclinical adjuvant discovery and development are inefficient. To enhance adjuvant identification, we developed a protocol based on in vitro screening of human primary leukocytes.

Summary

We describe a methodology utilizing high-throughput and high-content screening for novel adjuvant candidates that was used to screen a library of ~2,500 small molecules via a 384-well quantitative combined cytokine and flow cytometry immunoassay in primary human peripheral blood mononuclear cells (PBMCs) from 4 healthy adult study participants. Hits were identified based on their induction of soluble cytokine (TNF, IFNg and IL-10) secretion and PBMC maturation (CD 80/86, Ox40, and HLA-DR) in at least two of the four donors screened. From an initial set of 197 compounds identified using these biomarkers-an 8.6% hit rate-we downselected to five scaffolds that demonstrated robust efficacy and potency in vitro and evaluated the top hit, vinblastine sulfate, for adjuvanticity in vivo. Vinblastine sulfate significantly enhanced murine humoral responses to recombinant SARS-CoV-2 spike protein, including a four-fold enhancement of IgG titer production when compared to treatment with the spike antigen alone. Overall, we outline a methodology for discovering immunomodulators with adjuvant potential via high-throughput screening of PBMCs in vitro that yielded a lead compound with in vivo adjuvanticity.

Trends in Adult and Elderly Vaccination: Focus on Vaccination Practices in Tunisia and Morocco

Vaccine preventable diseases (VPDs) are a prevailing concern among the adult population, despite availability of vaccines. Unlike pediatric vaccination programs, adult vaccination programs lack the required reach, initiative, and awareness. Clinical studies and real-world data have proven that vaccines effectively reduce the disease burden of VPDs and increase life expectancy. In Tunisia and Morocco, the national immunization program (NIP) focuses more on pediatric vaccination and have limited vaccination programs for adults. However, some vaccination campaigns targeting adults are organized. For example, influenza vaccination campaigns prioritizing at risk adults which includes healthcare professionals, elderly, and patients with comorbidities. Women of childbearing age who have never been vaccinated or whose information is uncertain are recommended to receive tetanus vaccination. Tunisia NIP recommends rubella vaccine mainly for women of childbearing age, while in Morocco, national vaccination campaigns were organized for girls and women (up to 24 years of age) to eliminate rubella. Further, travelers from both countries are recommended to follow all requirements and recommendations in the travel destination. The objective of this manuscript is to provide an overview of the global disease burden of common VPDs including (but not limited to) meningococcal diseases, pneumococcal diseases, hepatitis, and influenza. The review also provides an overview of clinical data and guidelines/recommendations on adult vaccination practices, with special focus on Tunisia and Morocco. Some European and North American countries have concrete recommendations and strategies for adult vaccination to keep the VPDs in check. In Morocco and Tunisia, although, there are sporadic adult vaccination initiatives, the efforts still need upscaling and endorsements to boost vaccination awareness and uptake. There is a need to strengthen strategies in both countries to understand the disease burden and spread awareness. Additional studies are needed to generate economic evidence to support cost-effectiveness of vaccines. Integration of private and public healthcare systems may further improve vaccination uptake in adults.

The economic burden of influenza among adults aged 18 to 64: A systematic literature review

While the economic burden of influenza infection is well described among adults aged 65 and older, less is known about younger adults. A systematic literature review was conducted to describe the economic burden of seasonal influenza in adults aged 18 to 64 years, to identify the main determinants of direct and indirect costs, and to highlight any gaps in the existing published evidence. MEDLINE and Embase were searched from 2007 to February 7, 2020, for studies reporting primary influenza-related cost data (direct or indirect) or absenteeism data. Of the 2613 publications screened, 51 studies were included in this review. Half of them were conducted in the United States, and 71% of them described patients with influenza-like illness rather than laboratory-confirmed disease. Only 12 studies reported cost data specifically for at-risk populations. Extracted data highlighted that within the 18- to 64-year-old group, up to 88% of the economic burden of influenza was attributable to indirect costs, and up to 75% of overall direct costs were attributable to hospitalizations. Furthermore, within the 18- to 64-year-old group, influenza-related costs increased with age and underlying medical conditions. The reported cost of influenza-related hospitalizations was found to be up to 2.5 times higher among at-risk populations compared with not-at-risk populations. This review documents the considerable economic impact of influenza among adults aged 18 to 64. In this age group, most of the influenza costs are indirect, which are generally not recognized by decision makers. Future studies should focus on at-risk subgroups, lab-confirmed cases, and European countries.

Adult Vaccination in the United Arab Emirates—A Physicians' Knowledge and Knowledge Sources Study

Background

A lack of knowledge on adult vaccination has been documented among physicians. They play a critical role in promoting adult vaccines. This study aimed to review the status of adult vaccination in the United Arab Emirates (UAE) and evaluate physicians' knowledge and knowledge sources regarding adult vaccines.

Methods

Local, regional, and global adult vaccination guidelines were reviewed. A 40-item questionnaire was used to collect data from physicians from June to October 2020, using convenience and snowball sampling. Knowledge score was calculated, and predictors identified using Mann–Whitney U and Kruskal–Wallis H-tests. Ordinary Least Squares regression was used for Multivariate Analysis.

Results

A total of 500 responses were included. A quarter were internists, and another quarter were family physicians. Fifty-seven percent were medical interns and residents. Both perceived and actual knowledge of adult vaccination were low. Bivariate analysis showed knowledge depending on department, level of training, workplace, and perceived knowledge. All remained significant after multivariable regression except workplace. International and local guidelines were the most common knowledge sources. Forty-two percent were unable to access the local guidelines.

Conclusions

Physicians' knowledge was poor and local guidelines were not clear or easily accessible. Participants were highly receptive to guidance and practice with adult vaccines.

Community pharmacists workforce readiness to deliver vaccination services: A cross-sectional study from Jordan

This study assesses Jordanian community pharmacists’ readiness and willingness to deliver vaccination services in their practice sites. Between February and April 2021, a self‐administered online questionnaire was distributed via social media, WhatsApp messages, and personal communication. The questionnaire targeted practicing community pharmacies. Descriptive and inferential data analysis was carried out. A total of 403 community pharmacists participated in the study. Almost 146 (36%) community pharmacists reported vaccinating patients in their practice sites. However, readiness assessment revealed that only 54 (13.4%) pharmacists received the required training and qualifications. Moreover, 33 (8.2%) study participants worked in adequately equipped and designed community pharmacies. Overall, surveyed participants held positive attitudes toward their involvement in vaccination services: 260 (64.5%) pharmacists were willing to vaccinate patients, and 227 (65.0%) out of unready, unqualified, participants were willing to get needed training and qualifications. According to study participants, regulatory and professional bodies (Ministry of Health, Jordan Pharmacists Association) are influential in supporting pharmacist‐vaccinators. Among the investigated factors, organizational structure and employment status were significantly associated with pharmacists’ readiness to deliver vaccination. This study revealed that further work is needed to increase pharmacists’ and pharmacies’ readiness to deliver vaccination services and that regulators should follow a more active approach in highlighting the importance of training and the impact of training in patients’ safety and satisfaction.

The Value(s) of Vaccination: Building the Scientific Evidence According to a Value-Based Healthcare Approach

Objectives

To provide a new value-based immunization approach collating the available scientific evidence on the topic.

Methods

Four value pillars (personal, allocative, technical, and societal) applied to vaccination field were investigated. A systematic literature review was performed querying three database from December 24th, 2010 to May 27th, 2020. It included studies on vaccine-preventable diseases (VPDs) that mentioned the term value in any part and which were conducted in advanced economies. An in-depth analysis was performed on studies addressing value as key element.

Results

Overall, 107 studies were considered. Approximately half of the studies addressed value as a key element but in most of cases (83.3%) only a single pillar was assessed. Furthermore, the majority of papers addressed the technical value by looking only at classical methods for economic assessment of vaccinations whereas very few dealt with societal and allocative pillars.

Conclusions

Estimating the vaccinations value is very complex, even though their usefulness is certain. The assessment of the whole value of vaccines and vaccinations is still limited to some domains and should encompass the wider impact on economic growth and societies.

Analysis of the safety and immunogenicity profile of an azoximer bromide polymer-adjuvanted subunit influenza vaccine

A systematic review of clinical trials conducted with a low-dose inactivated influenza vaccine adjuvanted by azoximer bromide (AZB, Polyoxidonium), was performed to compare vaccine reactogenicity against non-adjuvant vaccines. We also assessed whether lower amounts of antigen per viral strain in AZB-adjuvanted vaccines affected antibody responses. A robust search strategy identified scientific publications reporting 30 clinical trials, comprising data on 11,736 participants and 86 trial arms, for inclusion in the analysis. Local reaction rates (R _lr) appeared to be lower in AZB-adjuvanted vaccine treatment arms versus comparator vaccine treatment arms. Meta‑regression analysis revealed that AZB did not contribute to vaccine reactogenicity. Post-vaccination geometric mean titres in those exposed to AZB-adjuvanted vaccine and comparator vaccine treatment arms were similar in both children and adults aged 18-60 years, implying an antigen-sparing effect by AZB.

Social determinants of health and adult influenza vaccination: a nationwide claims analysis

BACKGROUND: The health and economic benefits of the annual influenza vaccine are well documented, yet vaccination rates in the United States missed the Healthy People 2020 goal and remain a focus of Healthy People 2030 efforts. By identifying underlying reasons for low annual influenza vaccination, social elements that need targeting may be identified and could guide future interventions or policy development to achieve vaccination goals and improve overall public health. OBJECTIVE: To determine the influence of certain social determinants of health on adherence to annual influenza vaccination in American adults. METHODS: This was a retrospective cohort analysis using data from IBM MarketScan Commercial Claims and Encounters Database and national Medicare 5% sample data from 2013 to 2016. Study eligibility criteria included adults (aged 18 years and older) who were continuously enrolled for 3 influenza seasons between 2013 and 2016. Receipt of the influenza vaccine was counted over 3 consecutive influenza seasons, and select social determinants were extracted from publicly available sources. Patient characteristics, health resource utilization, and selected social determinants of health were included in bivariate and multivariate logistic regression analyses to determine their association with annual influenza vaccination. RESULTS: 6,694,571 adults across employer-sponsored and Medicare coverage groups were analyzed, of which 14.7% of Medicare-enrolled adults and 9.2% of commercially enrolled adults were vaccinated in all 3 seasons. Higher proportions of vaccine adherence (ie, all 3 seasons) were observed among females (9.6% vs 8.7% [commercial], 15.0% vs 14.4% [Medicare]), the immunocompromised (11.8% vs 8.3% [commercial], 15.9% vs 13.6% [Medicare]), rural residents (10.5% vs 9.0% [commercial], 15.4% vs 14.6% [Medicare]; all P < 0.0001), and those enrolled in a high-deductible health plan (10.3%). Multivariable logistic regression models indicated that the odds of vaccine adherence tended to be higher in areas of higher poverty (OR=1.012; 95% CI = 1.01-1.02 [commercial], OR=1.01; 95% CI = 1.01-1.01 [Medicare]) yet lower in areas with higher proportions of Democratic voters (OR=0.998; 95% CI = 0.998-0.998 [commercial], OR = 0.996; 95% CI = 0.996-0.997 [Medicare]). Among commercially insured adults, the odds of vaccine adherence were higher in areas of higher health literacy (OR=1.036; 95% CI = 1.036-1.037), but this effect was not observed among Medicare members. Conversely, the odds of vaccine adherence increased as the proportion of those residing in areas of limited Internet access increased (OR=1.007; 95% CI = 1.004-1.010) among Medicare members only. CONCLUSIONS: Key social determinants of health are important factors of vaccine adherence and can guide policy and intervention efforts toward addressing potential hesitancy. A deeper assessment of other contributing social factors is needed in seasonal influenza and other vaccines to better interpret the vaccine-seeking behaviors of adults. DISCLOSURES: This study received no outside funding. Gatwood, Hagemann, Hohmeier, and Chiu declare vaccine-related grant funding from Merck & Co. and GlaxoSmithKline for vaccine research unrelated to the current study. Ramachandran declares vaccine-related grant funding from Glaxo-SmithKline for research unrelated to the current study. Shuvo and Behal have nothing to disclose. Findings described in this study were presented as a poster and podium at the Academy of Managed Care Pharmacy Nexus 2020 Virtual meeting, October 19-23, 2020.

Estimates of the Health and Economic Burden of Pneumococcal Infections Attributable to the 15-Valent Pneumococcal Conjugate Vaccine Serotypes in the USA

Introduction

Despite the availability of vaccines, pneumococcal disease (PD) is associated with high clinical and economic burden, mainly caused by non-vaccine serotypes and certain vaccine-type serotypes. V114 is a 15-valent pneumococcal conjugate vaccine (PCV) that contains two epidemiologically important serotypes, 22F and 33F, in addition to the 13 serotypes in 13-valent PCV (PCV13). This study quantified the epidemiologic and economic burden of PD attributable to V114 serotypes among adults in the USA.

Methods

A Markov model was used to estimate the burden of V114 serotypes in a hypothetical, non-vaccinated cohort of US adults ≥ 19 years of age who were tracked from 2019 until death. The model calculated all the invasive pneumococcal disease (IPD) and non-bacteremic pneumococcal pneumonia (NBPP) cases, deaths, and costs. Economic burden was estimated from a healthcare payer perspective (2019 US dollars) and discounted at 3%.

Results

The model estimated 415,229 and 10.3 million lifetime cases of V114-type IPD and NBPP, respectively. Serotypes 22F and 33F caused approximately 33% of IPD cases and 20% of NBPP cases, while serotype 3 accounted for approximately 36% of IPD cases and 13% of NBPP cases. V114 serotypes caused 472,063 total lifetime deaths. Total discounted lifetime costs attributable to V114 serotypes were $44.8 billion US dollars.

Conclusions

In this hypothetical model of a non-vaccinated cohort of US adults, V114 serotypes were associated with a substantial health and economic burden, the majority of which was attributable to serotypes 3, 22F, and 33F. The addition of V114 to the national vaccination recommendations may help to reduce the epidemiologic and economic burden associated with PD in adults ≥ 19 years of age in the USA by providing increased coverage of these serotypes.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40121-022-00588-x.

Clinical and economic outcomes associated with respiratory syncytial virus vaccination in older adults in the United States

BACKGROUND

Respiratory syncytial virus (RSV) is an important cause of lower respiratory infections and hospitalizations among older adults. We aimed to estimate the potential clinical benefits and economic value of RSV vaccination of older adults in the United States (US).

METHODS

We developed an economic model using a decision-tree framework to capture outcomes associated with RSV infections in US adults aged ≥ 60 years occurring during one RSV season for a hypothetical vaccine versus no vaccine. Two co-base-case epidemiology sources were selected from a targeted review of the US literature: a landmark study capturing all RSV infections and a contemporary study reporting medically attended RSV that also distinguishes mild from moderate-to-severe disease. Both base-case analyses used recent data on mortality risk in the year after RSV hospitalizations. Direct medical costs and quality-adjusted life-years (QALYs) lost per case were obtained from the literature and publicly available sources. Model outcomes included the population-level clinical and economic RSV disease burden among older adults, potential vaccine-avoidable disease burden, and the potential value-based price of a vaccine from a third-party payer perspective.

RESULTS

Our two base-case analyses estimated that a vaccine with 50% efficacy and coverage matching that of influenza vaccination would prevent 43,700-81,500 RSV hospitalizations and 8,000-14,900 RSV-attributable deaths per RSV season, resulting in 1,800-3,900 fewer QALYs lost and avoiding $557-$1,024 million. Value-based prices for the co-base-case analyses were $152-$299 per vaccination at a willingness to pay of $100,000/QALY gained. Sensitivity analyses found that the economic value of vaccination was most sensitive to RSV incidence and increased posthospitalization mortality risks.

CONCLUSIONS

Despite variability and gaps in the epidemiology literature, this study highlights the potential value of RSV vaccination for older adults in the US. Our analysis provides contemporary estimates of the population-level RSV disease burden and insights into the economic value drivers for RSV vaccination.

Economic Burden of Pneumococcal Disease in Individuals Aged 15 Years and Older in the Liguria Region of Italy

Despite the availability of vaccines against Streptococcus pneumoniae, the global incidence and economic cost of pneumococcal disease (PD) among adults is still high. This retrospective cohort analysis estimated the cost of emergency department (ED) visits/hospitalizations associated with non-invasive pneumonia and invasive pneumococcal disease among individuals ≥15 years of age in the Liguria region of Italy during 2012–2018. Data from the Liguria Region Administrative Health Databases and the Ligurian Chronic Condition Data Warehouse were used, including hospital admission date, length of stay, discharge date, outpatient visits, and laboratory/imaging procedures. A ≥30-day gap between two events defined a new episode, and patients with ≥1 ED or inpatient claim for PD were identified. The total mean annual number of hospitalizations for PD was 13,450, costing ~€49 million per year. Pneumonia accounted for the majority of hospitalization costs. The median annual cost of hospitalization for all-cause pneumonia was €38,416,440 (per-capita cost: €26.78) and was €30,353,928 (per-capita cost: €20.88) for pneumococcal and unspecified pneumonia. The total number and associated costs of ED visits/hospitalizations generally increased over the study period. PD still incurs high economic costs in adults in the Liguria region of Italy.

Costs related to immunopreventable diseases: Brazil and its geographic areas (immunopreventable diseases' costs in Brazil)

INTRODUCTION

The occurrence of the immunopreventable diseases in a population global reality.

OBJECTIVE

To discriminate the direct costs of the hospitalizations from the immunopreventable diseases in the Unified Health System (SUS), in Brazil and their areas, between 2008 and 2018.

METHODS

A population, observational, descriptive and retrospective study, with data from the information supplied by the DATASUS website, these data were collected during the 2019.

RESULTS

It was identified 457,479 hospitalizations in the period; with a total of 2,450,870 days of hospital stay, with total costs of R$389,243,264.85. Only the disease mumps presented a growing tendency in whole areas; the chickenpox was decreasing; the illness whooping cough, yellow fever and tetanus were stationary in this period.

CONCLUSIONS

The costs related to immunopreventable diseases were relevant in all the Brazil areas, with tendencies different between the geographic areas and between the several illnesses analysed.

The impact of community pharmacy utilization of immunization information systems on vaccination rates: Results of a clustered randomized controlled trial

BACKGROUND

Adult immunization rates in the United States remain low. More convenient access to immunization information systems (IIS) may improve vaccination rates.

OBJECTIVE

The objective of this multilevel, clustered, randomized controlled study was to measure the impact of providing pharmacists with software and training to query IIS for patient vaccine history/recommendations on adult influenza, pneumococcal, herpes zoster, and Td/Tdap vaccination rates.

METHODS

California Rite Aid pharmacy districts were randomized into intervention/control groups using stratified randomization based on baseline influenza vaccination rates. Store demographic characteristics were collected at baseline (January 1-December 31, 2018). During follow-up (April 1, 2019-March 31, 2020), intervention group stores received access to ImmsLink, software that allows health care providers to review immunization records from IIS and identify a patient's recommended vaccinations. The difference-in-difference between intervention and control groups compared the changes in vaccination rates from baseline to follow-up by calculating adjusted ratios of risk ratios (RRRs). Analysis was performed at the store level.

RESULTS

Thirty-six districts comprising 501 Rite Aid stores (intervention: n = 244 stores; control: n = 257) were included. We found no significant differences in vaccination rates between groups: influenza, 19-64 years (adjusted RRR 0.99 [95% CI 0.83-1.17]); influenza, ≥65 years (1.02 [0.86-1.22]); herpes zoster (1.07 [0.90-1.28]); pneumococcal (0.95, 0.80-1.14); and Td/Tdap (0.88, 0.73-1.05). Reasons that recommended vaccines were not given in the intervention group included patient being deferred to future visit, patient declining, patient having already received the vaccination, patient declining because of cost, or vaccine being unavailable. Overall, pharmacist engagement with ImmsLink was low.

CONCLUSION

Providing pharmacists with software and training to query IIS did not improve vaccination rates compared with control pharmacies in this study. Factors such as an inconvenient interface or inadequate training or motivation may have caused low engagement with the software and should be considered in future interventions.

State-Level Variations and Factors Associated with Adult Vaccination Coverage: A Multilevel Modeling Approach

BACKGROUND

Adult vaccination rates in the USA are generally low and fall short of public health goals.

OBJECTIVES

Our aim was to evaluate the effect of state-level characteristics on adult vaccination coverage in the USA.

METHODS

This study was a cross-sectional, retrospective analysis of 2015-2017 Behavioral Risk Factor Surveillance System data, conducted from March to October 2019 and including seasonal influenza; pneumococcal; tetanus, diphtheria, and acellular pertussis (Tdap); and herpes zoster (HZ) vaccines. Multilevel logistic regression models examined interstate vaccination coverage variability and assessed the impact of state-level characteristics, with model-adjusted coverage estimated.

RESULTS

Model-adjusted vaccination coverage varied by state, with 35.1-48.1% coverage for influenza (2017), 68.2-80.8% for pneumococcal (2017), 21.9-46.5% for Tdap (2016), and 30.5-50.9% for HZ (2017). Characteristics associated with vaccination included state-level insurance coverage, pharmacists' vaccination authority, vaccination exemptions, and adult immunization information systems participation, as well as individual-level measures of income and education. After adjusting for these factors, substantial interstate heterogeneity remained.

CONCLUSIONS

Model-adjusted coverage was generally low and varied by state. A small number of state-level characteristics partially explained interstate coverage variability. This and future research assessing additional state characteristics may help determine policies most likely to increase adult vaccination.

Cost-benefit analysis of vaccination against four preventable diseases in older adults: Impact of an aging population

OBJECTIVE

This exploratory study estimates the economic value of the current vaccination program and increased coverage against four preventable diseases in older adults in the United States (US).

METHODS

A population-based, age-structured economic model was used to conduct a cost-benefit analysis of vaccination against influenza, pertussis, herpes zoster, and pneumococcal disease among US adults aged 50 years and older, accounting for aging of the population. The model used separate decision trees for each disease to project the discounted number of vaccinated individuals, number of disease cases, and direct medical and indirect costs (2018 US$) over a 30-year period. Benefit-cost ratios (BCRs) and net present values were calculated for two primary analyses comparing current vaccination coverage versus no vaccination and comparing increased coverage versus current coverage. Key parameter values were varied in deterministic sensitivity analyses.

RESULTS

Current adult vaccination coverage (vs. no vaccination) is estimated to result in nearly 65 million averted disease cases, $185 billion averted costs of cases, and $136 billion in incremental vaccination costs over a 30-year period from a societal perspective (BCR = 1.4). Increased vaccination coverage (vs. current coverage) is associated with over 33 million additional averted disease cases, $96 billion additional averted costs of cases, and nearly $83 billion in incremental vaccination costs, resulting in a societal BCR of 1.2 over 30 years. Deterministic sensitivity analyses demonstrated that results were most sensitive to disease incidence, vaccine efficacy, and productivity costs for time required for vaccination.

CONCLUSIONS

Study results highlight the economic value of vaccination programs for older adults in the US and indicate that efforts to further increase vaccination coverage may be warranted and economically justifiable.

Preferences for herpes zoster vaccination among adults aged 50 years and older in the United States: results from a discrete choice experiment

BACKGROUND

Most adults, and disproportionately fewer African-Americans, have not received herpes zoster (HZ) vaccination despite current recommendations. This study (GSK study identifiers: 208677/HO-17-18066) assessed HZ vaccination preferences among adults aged ≥ 50 years.

RESEARCH DESIGN AND METHODS

In this discrete choice experiment, respondents chose among a 'no vaccine' option and two HZ vaccine profiles, characterized by seven attributes, in a series of choice questions. Random-parameters logit results were used to predict likely vaccine uptake. Subgroup and latent class analysis of African-American's preferences were performed.

RESULTS

The preference weight for choosing HZ vaccines over no vaccine was statistically significant among the 1,454 respondents (71.9% whites; 25.2% African-Americans). Out-of-pocket (OOP) cost and vaccine effectiveness (VE) were the most important attributes. The African-American and the non-African-American subgroups had statistically significant differences in preferences (χ² = 59.91, p < 0.001), mainly driven by OOP cost and VE. Latent class analysis identified three groups of African-American respondents with systematically different preferences; two comprised likely-vaccinators, with one being more cost sensitive at lower price thresholds, and one likely non-vaccinators.

CONCLUSIONS

For all respondents, HZ vaccine choices were most sensitive to total OOP cost, followed by VE.

Promoting, seeking, and reaching vaccination services: A systematic review of costs to immunization programs, beneficiaries, and caregivers

INTRODUCTION

Understanding the costs to increase vaccination demand among under-vaccinated populations, as well as costs incurred by beneficiaries and caregivers for reaching vaccination sites, is essential to improving vaccination coverage. However, there have not been systematic analyses documenting such costs for beneficiaries and caregivers seeking vaccination.

METHODS

We searched PubMed, Scopus, and the Immunization Delivery Cost Catalogue (IDCC) in 2019 for the costs for beneficiaries and caregivers to 1) seek and know how to access vaccination (i.e., costs to immunization programs for social mobilization and interventions to increase vaccination demand), 2) take time off from work, chores, or school for vaccination (i.e., productivity costs), and 3) travel to vaccination sites. We assessed if these costs were specific to populations that faced other non-cost barriers, based on a framework for defining hard-to-reach and hard-to-vaccinate populations for vaccination.

RESULTS

We found 57 studies describing information, education, and communication (IEC) costs, social mobilization costs, and the costs of interventions to increase vaccination demand, with mean costs per dose at $0.41 (standard deviation (SD) $0.83), $18.86 (SD $50.65) and $28.23 (SD $76.09) in low-, middle-, and high-income countries, respectively. Five studies described productivity losses incurred by beneficiaries and caregivers seeking vaccination ($38.33 per person; SD $14.72; n = 3). We identified six studies on travel costs incurred by beneficiaries and caregivers attending vaccination sites ($11.25 per person; SD $9.54; n = 4). Two studies reported social mobilization costs per dose specific to hard-to-reach populations, which were 2-3.5 times higher than costs for the general population. Eight studies described barriers to vaccination among hard-to-reach populations.

CONCLUSION

Social mobilization/IEC costs are well-characterized, but evidence is limited on costs incurred by beneficiaries and caregivers getting to vaccination sites. Understanding the potential incremental costs for populations facing barriers to reach vaccination sites is essential to improving vaccine program financing and planning.

Next Generation of Computationally Optimized Broadly Reactive HA Vaccines Elicited Cross-Reactive Immune Responses and Provided Protection against H1N1 Virus Infection

Vaccination is the best way to prevent influenza virus infections, but the diversity of antigenically distinct isolates is a persistent challenge for vaccine development. In order to conquer the antigenic variability and improve influenza virus vaccine efficacy, our research group has developed computationally optimized broadly reactive antigens (COBRAs) in the form of recombinant hemagglutinins (rHAs) to elicit broader immune responses. However, previous COBRA H1N1 vaccines do not elicit immune responses that neutralize H1N1 virus strains in circulation during the recent years. In order to update our COBRA vaccine, two new candidate COBRA HA vaccines, Y2 and Y4, were generated using a new seasonal-based COBRA methodology derived from H1N1 isolates that circulated during 2013-2019. In this study, the effectiveness of COBRA Y2 and Y4 vaccines were evaluated in mice, and the elicited immune responses were compared to those generated by historical H1 COBRA HA and wild-type H1N1 HA vaccines. Mice vaccinated with the next generation COBRA HA vaccines effectively protected against morbidity and mortality after infection with H1N1 influenza viruses. The antibodies elicited by the COBRA HA vaccines were highly cross-reactive with influenza A (H1N1) pdm09-like viruses isolated from 2009 to 2021, especially with the most recent circulating viruses from 2019 to 2021. Furthermore, viral loads in lungs of mice vaccinated with Y2 and Y4 were dramatically reduced to low or undetectable levels, resulting in minimal lung injury compared to wild-type HA vaccines following H1N1 influenza virus infection.