Immunosenescence: influenza vaccination and the elderly

Similar humoral responses but distinct CD4+ T cell transcriptomic profiles in older adults elicited by MF59 adjuvanted and high dose influenza vaccines

Older age (≥ 65 years) is associated with impaired responses to influenza vaccination, leading to the preferential recommendation of MF59-adjuvanted (MF59Flu) or high-dose (HDFlu) influenza vaccines for this age group in the United States. Herein, we characterized transcriptomic profiles of CD4+ T cells isolated from 234 recipients (≥ 65 years) of either MF59Flu or HDFlu vaccine, prior to vaccination and 28 days thereafter. We identified 412 and 645 differentially expressed genes (DEGs) in CD4+ T cells of older adults after receiving MF59Flu and HDFlu, respectively. DEGs in CD4+ T cells of MF59Flu recipients were enriched in 14 KEGG pathways, all of which were downregulated. DEGs in CD4+ T cells of HDFlu recipients were enriched in 11 upregulated pathways and 20 downregulated pathways. CD4+ T cells in both vaccine groups shared 50 upregulated genes and 75 downregulated genes, all of which were enriched in 7 KEGG pathways. The remaining 287 and 520 DEGs were specifically associated with MF59Flu and HDFlu, respectively. Unexpectedly, none of these DEGs was significantly correlated with influenza A/H3N2-specific HAI titers, suggesting these DEGs at the individual level may have a limited role in protection against influenza. Our findings emphasize the need for further investigation into other factors influencing immunity against influenza in older adults.

Immunoaging at Early Ages Could Drive a Higher Comorbidity Burden in People with HIV on Antiretroviral Therapy Compared with the Uninfected Population

This is an observational, cross-sectional, comparative case-control, pilot study aimed at assessing the impact of HIV infection and age on immunological markers in people with HIV (PWH) on antiretroviral therapy (ART). The study included 40 PWH on ART, divided into two age groups (40-45 years vs. ≥60 years), and 30 HIV-uninfected controls matched by sex and age. The results show that older PWH on ART had more comorbidities and a higher frequency of CD8 T cells compared to older controls, with a significant decrease in CD8 naïve T cells with age. Additionally, younger PWH on ART exhibited higher frequencies of activated CD8 T cells and elevated levels of inflammatory markers (sCD14, IL-6) compared to age-matched controls, with values similar to those of older PWH on ART. These findings suggest that younger PWH on ART may experience accelerated immunoaging, highlighting the need for early interventions in this population.

Safety, reactogenicity and immunogenicity of an intranasal seasonal influenza vaccine adjuvanted with gram-positive matrix (GEM) particles (FluGEM): A randomized, double-blind, controlled, ascending dose study in healthy adults and elderly

BACKGROUND

Intranasal administration of respiratory vaccines offers many advantages such as eliciting both systemic and mucosal immunity at the point of viral entry. Immunogenicity of intranasal vaccination can be improved through the use of adjuvants. Bacteria-like particles derived fromLactococcus lactishave the potential to serve as a vaccine adjuvant.This clinical study investigated the safety, reactogenicity and immunogenicity of intranasal seasonal influenza vaccine adjuvanted with gram-positive matrix particles (FluGEM®).

METHODS

This was a first-in-human, randomized, double-blind, controlled, dose-escalation study performed at the Centre for Human Drug Research (CHDR), the Netherlands. Participants aged 18-49 were randomized in a 3:1 ratio to receive FluGem® in ascending doses (two-dose regimens) together with a standard trivalent inactivated influenza vaccine or unadjuvanted TIV only. Primary outcomes were safety and tolerability. Secondary outcomes were serum hemagglutination inhibition (HI) antibody titers and mucosal IgA. The most immunogenic dose was used in an additionalelderly cohort (>65 years).

RESULTS

Ninty participants were included. Intranasal FluGem®was safe and well tolerated. The majority of adverse events were mild (97.4 %) with (un)solicited adverse events comparable across all dose levels and control groups. All groups showed geometric mean increases ≥ 2.5-fold. Seroconversion (≥40 % participants) was achieved at both day 21 (single-dose) and 42 (two-dose) for the 1.25 mg dose and on day 42 (two-dose only) for the 2.5 mg dose. Highest geometric mean IgA increases were observed in the 1.25 mg group on day 21. Immunogenicity was less pronounced in elderly.

CONCLUSIONS

Intranasal vaccination of FluGEM®was safe and tolerable in healthy adult volunteers aged 18-49 years and 65 and older. Highest immunogenicity was observed for 1.25 mg and 2.5 mg doses (compared to 5 mg) suggesting a potential non-linear dose-response relationship.More research is needed to further investigate the capabilities of bacteria-like peptides as adjuvants.

Protection against influenza hospitalizations from enhanced influenza vaccines among older adults: A systematic review and network meta-analysis

BACKGROUND

Influenza vaccines are available to help protect persons aged ≥65 years, who experience thousands of influenza hospitalizations annually. Because some influenza vaccines may work better than others, we sought to assess benefit of high-dose (HD), adjuvanted (ADJ), and recombinant (RIV) influenza vaccines ("enhanced influenza vaccines") compared with standard-dose unadjuvanted influenza vaccines (SD) and with one another for prevention of influenza-associated hospitalizations among persons aged ≥65 years.

METHODS

We searched MEDLINE, Embase, CINAHL, Scopus, and Cochrane Library to identify randomized or observational studies published between January 1990 and October 2023 and reporting relative vaccine effectiveness (rVE) of HD, ADJ, or RIV for prevention of influenza-associated hospitalizations among adults aged ≥65 years. We extracted study data, assessed risk of bias, and conducted random-effects network meta-analysis and meta-regression.

RESULTS

We identified 32 studies with 90 rVE estimates from five randomized and 27 observational studies (71,459,918 vaccinated participants). rVE estimates varied across studies and influenza seasons. Pooled rVE from randomized studies was 20% (95% CI -54 to 59) and 25% (95% CI -19 to 53) for ADJ and HD compared with SD, respectively; rVE was 6% (95% CI -109 to 58) for HD compared with ADJ; these differences were not statistically significant. In observational studies, ADJ, HD, and RIV conferred modestly increased protection compared with SD (rVE ranging from 10% to 19%), with no significant differences between HD, ADJ, and RIV. With enhanced vaccines combined, rVE versus SD was 18% (95% CI 3 to 32) from randomized and 11% (95% CI 8 to 14) from observational evidence. Meta-regression of observational studies suggested that those requiring laboratory confirmation of influenza reported greater benefit of enhanced vaccines.

CONCLUSIONS

HD, ADJ, and RIV provided stronger protection than SD against influenza hospitalizations among older adults. No differences in benefit were observed in comparisons of enhanced influenza vaccines with one another.

Infectious Disease Updates for Primary Care

This article summarizes the situation with public health threats for primary care patients as of early 2024 and provides updates on strategies for the prevention, diagnosis, and treatment of common infections where new treatments and vaccines are available. For flu and COVID, an update on treatment is also provided-along with pearls useful for the busy primary care provider. The authors also discuss a new treatment option for drug-resistant vulvovaginal candidiasis and provide a balanced view of the increasingly popular technique of preventing bacterial sexually transmitted infections using doxycycline after condomless sex among men who have sex with men.

Deciphering immune responses: a comparative analysis of influenza vaccination platforms

Influenza still poses a significant challenge due to its high mutation rates and the low effectiveness of traditional vaccines. At present, antibodies that neutralize the highly variable hemagglutinin antigen are a major driver of the observed variable protection. To decipher how influenza vaccines can be improved, an analysis of licensed vaccine platforms was conducted, contrasting the strengths and limitations of their different mechanisms of protection. Through this review, it is evident that these vaccines do not elicit the robust cellular immune response critical for protecting high-risk groups. Emerging platforms, such as RNA vaccines, that induce robust cellular responses that may be additive to the recognized mechanism of protection through hemagglutinin inhibition may overcome these constraints to provide broader, protective immunity. By combining both humoral and cellular responses, such platforms could help guide the future influenza vaccine development.

Association of viral loads of influenza A (H3N2) with age and care setting on presentation-a prospective study during the 2022-2023 influenza season in Spain

OBJECTIVES

The aim of this study was to analyze the viral load (VL) using cycle threshold (Ct) in patients infected with influenza A (H3N2).

METHODS

This prospective study was conducted during the 2022-2023 influenza season in sentinel, non-sentinel, and hospitalized patients of Castilla y León (Spain). Respiratory samples were obtained from nasopharyngeal swabs and analyzed by quantitative reverse transcription-polymerase chain reaction specific for influenza A (H3N2) to obtain the Ct value.

RESULTS

A total of 1047 individuals were enrolled (174 [16.6%] sentinel, 200 [19.1%] non-sentinel, 673 [64.3%] hospitalized). The mean Ct value was lower in infants, young children, and in the elderly, with a sharp increase in the last from 65 years until 90 years. In addition, the lower Ct values were observed in non-sentinel patients and then in hospitalized patients, probably because non-sentinel are outpatients in the acute phase of the influenza infection.

CONCLUSIONS

A higher VL (lower Ct value) is related to the extreme ages of life: children and the elderly. Furthermore, a higher VL is related with the care setting, being probably higher in outpatients because they are in the acute phase of the disease and slightly lower in hospitalized patients because they are attended during the post-acute phase.

Non-specific effects of the inactivated influenza vaccine. A test-negative study: The inactivated influenza vaccine and SARS-CoV-2 infections

BACKGROUND

Previous research suggested that the inactivated influenza vaccine (IIV) may protect against SARS-CoV-2 infection or a severe course of COVID-19. These findings were however based on cohort studies, that are prone to confounding by indication. We examined the association between IIV and SARS-Cov-2 infection in a Dutch population using a test-negative design.

METHODS

This test-negative case-control study was conducted in adults (≥60) who tested because of COVID-19 like symptoms at community SARS-CoV-2 testing locations in the Netherlands during the period of November 8th 2021-March 11th 2022. Information on receipt of IIV in October-November 2021 was routinely collected at each visit. Logistic regression was used to calculate unadjusted, partially (sex, age, education level) and fully adjusted (COVID-19 vaccination, IIV 2020) odds ratios (ORs) for receipt of IIV in SARS-CoV-2 positive versus negative subjects. Differential effects on SARS-CoV-2 risk by time since IIV were investigated by including an interaction term for calendar time: November 2021-January 2022 vs February-March 2022.

RESULTS

In total, 1,832 participants were included in the main analysis, of whom 336 (18.3 %) had a positive SARS-CoV-2 test. No significant association between IIV and SARS-CoV-2 infection was found; fully adjusted OR of 1.07 (95 % CI: 0.78-1.49). The interaction term for time periods was not significant (1.04 [95 % CI: 0.51-2.15], p = 0.91). Results were robust in sensitivity analyses.

CONCLUSIONS

While earlier observational studies suggested a protective non-specific effect of IIV and SARS-CoV-2 infections, this smaller, but well controlled test-negative design study does not suggest an effect, either positive or negative. Larger test-negative design studies, or alternative designs such as the self-controlled case series design are needed to confirm these findings and provide more definite answers on the topic.

Cost-Effectiveness of Adjuvanted Quadrivalent Influenza Vaccine for Adults over 65 in France

BACKGROUND

In France, influenza accounts for an average of over one million consultations with GPs, 20,000 hospitalizations, and 9000 deaths per year, particularly among the over-65s. This study evaluates the cost-effectiveness of the adjuvanted quadrivalent influenza vaccine (aQIV) compared to standard (SD-QIV) and high-dose (HD-QIV) quadrivalent influenza vaccines for individuals aged 65 and older in France.

METHODS

The age-structured SEIR transmission model, calibrated to simulate a mean influenza season, incorporates a contact matrix to estimate intergroup contact rates. Epidemiological, economic, and utility outcomes are evaluated. Vaccine effectiveness and costs are derived from literature and national insurance data. Quality of life adjustments for influenza attack rates and hospitalizations are applied. Deterministic and probabilistic analyses are also conducted.

RESULTS

Compared to SD-QIV, aQIV demonstrates substantial reductions in healthcare utilization and mortality, avoiding 89,485 GP consultations, 2144 hospitalizations, and preventing 1611 deaths. Despite an investment of EUR 110 million, aQIV yields a net saving of EUR 14 million in healthcare spending. Compared to HD-QIV, aQIV saves 62 million euros on vaccination costs. Cost-effectiveness analysis reveals an incremental cost-effectiveness ratio of EUR 7062 per QALY.

CONCLUSIONS

This study highlights the cost-effectiveness of aQIV versus SD-QIV and HD-QIV, preventing influenza cases, hospitalizations, and deaths.

Protective MVA-ST Vaccination Robustly Activates T Cells and Antibodies in an Aged-Hamster Model for COVID-19

Aging is associated with a decline in immune system functionality. So-called immunosenescence may impair the successful vaccination of elderly people. Thus, improved vaccination strategies also suitable for an aged immune system are required. Modified Vaccinia virus Ankara (MVA) is a highly attenuated and replication-deficient vaccinia virus that has been established as a multipurpose viral vector for vaccine development against various infections. We characterized a recombinant MVA expressing a prefusion-stabilized version of SARS-CoV-2 S protein (MVA-ST) in an aged-hamster model for COVID-19. Intramuscular MVA-ST immunization resulted in protection from disease and severe lung pathology. Importantly, this protection was correlated with a potent activation of SARS-CoV-2 specific T-cells and neutralizing antibodies. Our results suggest that MVA vector vaccines merit further evaluation in preclinical models to contribute to future clinical development as candidate vaccines in elderly people to overcome the limitations of age-dependent immunosenescence.

Cost-effectiveness of cell-based influenza vaccine in France

OBJECTIVES

Annually in France, influenza results in over one million GP consultations, around 20,000 hospitalizations, and approximately 9,000 deaths. This study assesses the cost-effectiveness of cell-based quadrivalent influenza vaccine (QIVc) for those under 65, which enhances effectiveness avoiding egg-adaptation, compared to egg-based quadrivalent influenza vaccine (QIVe).

METHODS

An age-structured susceptible-exposed-infected-recovered (SEIR) transmission model, calibrated to represent an average influenza season based on French data from 2011 to 2019, integrates a contact matrix estimating intergroup contact rates. Evaluating epidemiological, economic and utility outcomes, the model includes vaccine effectiveness and medical costs from the existing literature and French national data. Adjustments to quality of life due to infection and hospitalization are also included. Uncertainty is explored through scenario and sensitivity analyses.

RESULTS

Compared to QIVe, QIVc significantly reduces healthcare utilization and mortality, preventing 49,946 GP consultations, 1,087 hospitalizations, and 231 deaths in France. Despite an initial investment of 7.6 million euros, QIVc achieves a net saving of 12 million euros in healthcare expenditures, making it a dominant cost-saving strategy. Probabilistic sensitivity analyses indicate dominance in 78% of 10,000 simulations.

CONCLUSIONS

Introducing cell-based influenza vaccines in the French immunization program prevents influenza cases, hospitalizations, death, while reducing costs versus egg-based influenza vaccines.

The Effect of Sex on the Incidence, Latency, Duration and Perceived Burden of Adverse Events Following Seasonal Influenza Vaccination in the Netherlands

INTRODUCTION

The annual reformulation of the seasonal influenza vaccine results in fluctuating frequencies and severity of adverse effects following immunization (AEFIs), which stresses the importance of pharmacovigilance. Also, sex-related factors are known to influence the development of AEFIs. This study aims to describe the difference in incidence and course (i.e., time-to-onset, time-to-recovery, and perceived burden) of AEFIs between males and females after seasonal influenza vaccination.

METHODS

We assessed data from cohort event monitoring studies, which were performed over nine consecutive years (2013-2021), each covering several months during the seasonal influenza campaign in the Netherlands. Participants reported information about AEFIs over a 30-day period in three questionnaires. The effect of sex, age, body mass index, study year, and comorbidities on the incidence of any AEFI, local reactions, fever and the five most reported AEFIs was analyzed using logistic regression. The difference in time-to-onset, time-to-recovery, and perceived burden between males and females was analyzed by the Kruskal-Wallis test.

RESULTS

The cohort included 7789 participants (53.0% females). Females had around 2.5-fold (p < 0.001) higher odds of developing any AEFI compared with males. Some study years and comorbidities were positively associated with AEFI incidence, whereas age was negatively associated. An AEFI had a significant shorter time-to-onset, a longer time-to-recovery, and a higher perceived burden in females compared to males.

CONCLUSION

Overall, the results confirm that females experience AEFIs more often than males. Additionally, this study shows that the course of AEFIs only partially differs between the sexes.

Baseline immune states (BIS) associated with vaccine responsiveness and factors that shape the BIS

Vaccines are among the greatest inventions in medicine, leading to the elimination or control of numerous diseases, including smallpox, polio, measles, rubella, and, most recently, COVID-19. Yet, the effectiveness of vaccines varies among individuals. In fact, while some recipients mount a robust response to vaccination that protects them from the disease, others fail to respond. Multiple clinical and epidemiological factors contribute to this heterogeneity in responsiveness. Systems immunology studies fueled by advances in single-cell biology have been instrumental in uncovering pre-vaccination immune cell types and genomic features (i.e., the baseline immune state, BIS) that have been associated with vaccine responsiveness. Here, we review clinical factors that shape the BIS, and the characteristics of the BIS associated with responsiveness to frequently studied vaccines (i.e., influenza, COVID-19, bacterial pneumonia, malaria). Finally, we discuss potential strategies to enhance vaccine responsiveness in high-risk groups, focusing specifically on older adults.

The convergent evolution of influenza A virus: Implications, therapeutic strategies and what we need to know

Influenza virus infection, more commonly known as the 'cold flu', is an etiological agent that gives rise to recurrent annual flu and many pandemics. Dated back to the 1918- Spanish Flu, the influenza infection has caused the loss of many human lives and significantly impacted the economy and daily lives. Influenza virus can be classified into four different genera: influenza A-D, with the former two, influenza A and B, relevant to humans. The capacity of antigenic drift and shift in Influenza A has given rise to many novel variants, rendering vaccines and antiviral therapies useless. In light of the emergence of a novel betacoronavirus, the SARS-CoV-2, unravelling the underpinning mechanisms that support the recurrent influenza epidemics and pandemics is essential. Given the symptom similarities between influenza and covid infection, it is crucial to reiterate what we know about the influenza infection. This review aims to describe the origin and evolution of influenza infection. Apart from that, the risk factors entail the implication of co-infections, especially regarding the COVID-19 pandemic is further discussed. In addition, antiviral strategies, including the potential of drug repositioning, are discussed in this context. The diagnostic approach is also critically discussed in an effort to understand better and prepare for upcoming variants and potential influenza pandemics in the future. Lastly, this review encapsulates the challenges in curbing the influenza spread and provides insights for future directions in influenza management.

Contributions of cost-effectiveness analyses (CEA) to influenza vaccination policy for older adults in Europe

This review describes the importance of economic evaluations and real-world evidence (RWE) for the assessment of enhanced influenza vaccines for older adults in Europe. Individuals ≥65 years of age are at increased risk of severe influenza outcomes and many countries in Europe recommend enhanced vaccines for this population to mitigate immunosenescence. Some National Immunization Technical Advisory Groups (NITAGs) may preferentially recommend a specific enhanced vaccine, necessitating comparative economic evaluation and estimation of relative vaccine effectiveness between enhanced vaccine options in the absence of direct head-to-head efficacy data. Distinct approaches to economic modeling and cost-effectiveness analysis (CEA) guide national vaccination policies in Europe, including how underlying data, such as RWE, are used in these models. RWE is an important evidence source for input into CEA models based on disease factors (e.g., antigenic shift and seasonal variation) and practical factors (e.g., limitations of performing multiple randomized clinical trials to capture seasonal variation; the need to obtain relevant patient-oriented, real-world endpoints, such as hospitalizations). CEA is considered crucial to vaccine assessment among certain countries in Europe, but further harmonization of economic evaluations, including the use of RWE, across NITAGs in Europe may be of benefit, alongside standardized approaches for vaccine appraisal. In the future, more countries may use RWE as an input in CEA models to support NITAG recommendations for enhanced influenza vaccines in older populations, especially considering the value of RWE for the assessment of influenza epidemiology and vaccine effectiveness as stated by the World Health Organization, and the availability of a broad RWE base for certain enhanced vaccines.

Additional Burden Averted in the United States From Use of MF59-Adjuvanted Seasonal Influenza Vaccine Compared With Standard Seasonal Influenza Vaccine Among Adults ≥65 Years

Background

The MF59-adjuvanted trivalent inactivated influenza vaccine (aIIV3) is designed to overcome immunosenescence and enhance vaccine responses in older adults. We expanded on the Centers for Disease Control and Prevention (CDC) modeling method to estimate the number of additional influenza-related outcomes averted with aIIV3 versus generic quadrivalent inactivated influenza vaccine (IIV4) in adults ≥65 years over 3 influenza seasons (2017-2018 to 2019-2020) in the United States.

Methods

A static compartmental model was developed based on an existing CDC model with 2 previously recommended calculation methods that increased the accuracy of the model in providing estimates of burden averted. Model inputs included vaccine effectiveness, vaccine coverage, population counts, and disease burden estimates. Additional burden averted (symptomatic cases, outpatient visits, hospitalizations, intensive care unit [ICU] admissions, and deaths) was expressed as total incremental cases averted between the vaccines. Sensitivity analyses tested the resilience of the model results to uncertainties in model inputs.

Results

The model estimated that vaccination with aIIV3 versus IIV4 would avert 2.24 times as many symptomatic cases, outpatient visits, hospitalizations, ICU stays, and deaths during 2017-2018; the burden averted in 2018-2019 and 2019-2020 with aIIV3 would be 3.44 and 1.72 times that averted with IIV4, respectively. Disease burden estimates and relative vaccine effectiveness of aIIV3 had the greatest impact on model estimates.

Conclusions

Over 3 influenza seasons, the model estimated that aIIV3 was more effective than IIV4 in averting influenza-related outcomes, preventing 1.72 to 3.44 times as many influenza illnesses with proportionate decreases in related healthcare use and complications.

Immunogenicity and safety of quadrivalent influenza vaccine among young and older adults in Tianjin, China: implication of immunosenescence as a risk factor

BACKGROUND

Older adults are more vulnerable to seasonal influenza than younger adults. The immune responses of older persons to the influenza vaccine are usually poorer than those of young individuals, which is hypothesized due to immunosenescence. We conducted a study to evaluate the immunogenicity and safety of a quadrivalent inactivated influenza vaccine (IIV4) in a total of 167 young (< 65 years, n = 79) and older (≥ 65 years, n = 88) adults from October 2021 to March 2022 in Tianjin, China. A single dose was administered to all participants. Blood samples were collected and strain-specific hemagglutination inhibition (HAI) antibody titers were measured before and 21 to 28 days after vaccination. Safety information was also collected for 28 days and 6 months after vaccination. Differences in immunogenicity and safety were compared between young and old age groups, and multivariate logistic regression was used to estimate the effect of age and other factors on HAI antibody responses.

RESULTS

Overall, geometric mean titers (GMTs) against all four vaccine strains in older adults were lower than those in the young, whereas the seroconversion rates (SCRs) were similar. Multivariate logistic regression analysis showed that age, influenza vaccination history, and pre-vaccination HAI titers were independent factors affecting SCRs and seroprotection rates (SCRs). Older age had significant negative impact on SCRs against H1N1 (OR, 0.971; 95% CI: 0.944-0.999; P = 0.042) and B/Victoria (OR, 0.964; 95% CI: 0.937-0.992; P = 0.011). In addition, there was a significant negative correlation between chronological age (years) and post-vaccination HAI titers against H1N1 (rho = -0.2298, P < 0.0001), B/Victoria (rho = -0.2235, P = 0.0037), and B/Yamagata (rho = -0.3689, P < 0.0001). All adverse events were mild (grade 1 or grade 2) that occurred within 28 days after vaccination, and no serious adverse event was observed.

CONCLUSIONS

IIV4 is immunogenic and well-tolerated in young and older adults living in Tianjin, China. Our findings also indicate that age is an independent factor associated with poorer humoral immune responses to IIV4.

Real-World Evidence in Cost-Effectiveness Analysis of Enhanced Influenza Vaccines in Adults ≥ 65 Years of Age: Literature Review and Expert Opinion

Influenza vaccination can benefit most populations, including adults ≥ 65 years of age, who are at greater risk of influenza-related complications. In many countries, enhanced vaccines, such as adjuvanted, high-dose, and recombinant trivalent/quadrivalent influenza vaccines (aTIV/aQIV, HD-TIV/HD-QIV, and QIVr, respectively), are recommended in older populations to provide higher immunogenicity and increased relative vaccine efficacy/effectiveness (rVE) than standard-dose vaccines. This review explores how efficacy and effectiveness data from randomized controlled trials and real-world evidence (RWE) are used in economic evaluations. Findings from published cost-effectiveness analyses (CEA) on enhanced influenza vaccines for older adults are summarized, and the assumptions and approaches used in these CEA are assessed alongside discussion of the importance of RWE in CEA. Results from many CEA showed that adjuvanted and high-dose enhanced vaccines were cost-effective compared with standard vaccines, and that differences in rVE estimates and acquisition price may drive differences in cost-effectiveness estimates between enhanced vaccines. Overall, RWE and CEA provide clinical and economic rationale for enhanced vaccine use in people ≥ 65 years of age, an at-risk population with substantial burden of disease. Countries that consider RWE when making vaccine recommendations have preferentially recommended aTIV/aQIV, as well as HD-TIV/HD-QIV and QIVr, to protect older individuals.

A comprehensive insight on the challenges for COVID-19 vaccine: A lesson learnt from other viral vaccines

The aim of this study is to comprehensively analyze previous viral vaccine programs and identify potential challenges and effective measures for the COVID-19 vaccine program. Previous viral vaccine programs, such as those for HIV, Zika, Influenza, Ebola, Dengue, SARS, and MERS, were evaluated. Paramount challenges were identified, including quasi-species, cross-reactivity, duration of immunity, revaccination, mutation, immunosenescence, and adverse events related to viral vaccines. Although a large population has been vaccinated, mutations in SARS-CoV-2 and adverse events related to vaccines pose significant challenges. Previous vaccine programs have taught us that predicting the final outcome of the current vaccine program for COVID-19 cannot be determined at a given state. Long-term follow-up studies are essential. Validated preclinical studies, long-term follow-up studies, alternative therapeutic approaches, and alternative vaccines are necessary.

Hemagglutinin virus-like particles incorporated with membrane-bound cytokine adjuvants provide protection against homologous and heterologous influenza virus challenge in aged mice

BACKGROUND

Current influenza vaccines deliver satisfactory results in young people but are less effective in the elderly. Development of vaccines for an ever-increasing aging population has been an arduous challenge due to immunosenescence that impairs the immune response in the aged, both quantitatively and qualitatively.

RESULTS

To potentially enhance vaccine efficacy in the elderly, we investigated the immunogenicity and cross-protection of influenza hemagglutinin virus-like particles (HA-VLP) incorporated with glycosylphosphatidylinositol (GPI)-anchored cytokine-adjuvants (GPI-GM-CSF and GPI-IL-12) via protein transfer in aged mice. Lung viral replication against homologous and heterologous influenza viruses was significantly reduced in aged mice after vaccination with cytokine incorporated VLPs (HA-VLP-Cyt) in comparison to HA-VLP alone. Enhanced IFN-γ+CD4+ and IFN-γ+CD8+ T cell responses were also observed in aged mice immunized with HA-VLP-Cyt when compared to HA-VLP alone.

CONCLUSIONS

Cytokine-adjuvanted influenza HA-VLP vaccine induced enhanced protective response against homologous influenza A virus infection in aged mice. Influenza HA-VLP vaccine with GPI-cytokines also induced enhanced T cell responses correlating with better protection against heterologous infection in the absence of neutralizing antibodies. The results suggest that a vaccination strategy using cytokine-adjuvanted influenza HA-VLPs could be used to enhance protection against influenza A virus in the elderly.

The effect of metformin on influenza vaccine responses in nondiabetic older adults: a pilot trial

BACKGROUND

Aging is associated with progressive declines in immune responses leading to increased risk of severe infection and diminished vaccination responses. Influenza (flu) is a leading killer of older adults despite availability of seasonal vaccines. Geroscience-guided interventions targeting biological aging could offer transformational approaches to reverse broad declines in immune responses with aging. Here, we evaluated effects of metformin, an FDA approved diabetes drug and candidate anti-aging drug, on flu vaccination responses and markers of immunological resilience in a pilot and feasibility double-blinded placebo-controlled study.

RESULTS

Healthy older adults (non-diabetic/non-prediabetic, age: 74.4 ± 1.7 years) were randomized to metformin (n = 8, 1500 mg extended release/daily) or placebo (n = 7) treatment for 20 weeks and were vaccinated with high-dose flu vaccine after 10 weeks of treatment. Peripheral blood mononuclear cells (PBMCs), serum, and plasma were collected prior to treatment, immediately prior to vaccination, and 1, 5, and 10 weeks post vaccination. Increased serum antibody titers were observed post vaccination with no significant differences between groups. Metformin treatment led to trending increases in circulating T follicular helper cells post-vaccination. Furthermore, 20 weeks of metformin treatment reduced expression of exhaustion marker CD57 in circulating CD4 T cells.

CONCLUSIONS

Pre-vaccination metformin treatment improved some components of flu vaccine responses and reduced some markers of T cell exhaustion without serious adverse events in nondiabetic older adults. Thus, our findings highlight the potential utility of metformin to improve flu vaccine responses and reduce age-related immune exhaustion in older adults, providing improved immunological resilience in nondiabetic older adults.

A target-cell limited model can reproduce influenza infection dynamics in hosts with differing immune responses

We consider a hierarchy of ordinary differential equation models that describe the within-host viral kinetics of influenza infections: the IR model explicitly accounts for an immune response to the virus, while the simpler, target-cell limited TEIV and TV models do not. We show that when the IR model is fitted to pooled experimental murine data of the viral load, fraction of dead cells, and immune response levels, its parameters values can be determined. However, if, as is common, only viral load data are available, we can estimate parameters of the TEIV and TV models but not the IR model. These results are substantiated by a structural and practical identifiability analysis. We then use the IR model to generate synthetic data representing infections in hosts whose immune responses differ. We fit the TV model to these synthetic datasets and show that it can reproduce the characteristic exponential increase and decay of viral load generated by the IR model. Furthermore, the values of the fitted parameters of the TV model can be mapped from the immune response parameters in the IR model. We conclude that, if only viral load data are available, a simple target-cell limited model can reproduce influenza infection dynamics and distinguish between hosts with differing immune responses.

Vaccine-Preventable Diseases in Older Adults

Older adults are at an increased risk of vaccine-preventable diseases partly because of physiologic changes in the immune and other body systems related to age and/or accumulating comorbidities that increase the vulnerability to infections and decrease the response to vaccines. Strategies to improve the response to vaccines include using a higher antigenic dose (such as in the high-dose inactivated influenza vaccines) as well as adding adjuvants (such as MF59 in the adjuvanted inactivated influenza vaccine).

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

BACKGROUND

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Older Adults Who Maintained a Regular Physical Exercise Routine before the Pandemic Show Better Immune Response to Vaccination for COVID-19

BACKGROUND

In this study, we aimed to investigate the specific-antibody response to the COVID-19 vaccination and the immunophenotyping of T cells in older adults who were engaged or not in an exercise training program before the pandemic.

METHODS

Ninety-three aged individuals (aged between 60 and 85 years) were separated into 3 groups: practitioners of physical exercise vaccinated with CoronaVac (PE-Co, n = 46), or vaccinated with ChadOx-1 (PE-Ch, n = 23), and non-practitioners vaccinated with ChadOx-1 (NPE-Ch, n = 24). Blood samples were collected before (pre) and 30 days after vaccination with the second vaccine dose.

RESULTS

Higher IgG levels and immunogenicity were found in the PE-Ch and NPE-Ch groups, whereas increased IgA levels were found only in the PE-Ch group post-vaccination. The PE-Co group showed a positive correlation between the IgA and IgG values, and lower IgG levels post-vaccination were associated with age. Significant alterations in the percentage of naive (CD28+CD57-), double-positive (CD28+CD57+), and senescent (CD28-CD57+) CD4+ T and CD8+ T cells were found post-vaccination, particularly in the PE-Ch group.

CONCLUSIONS

The volunteers vaccinated with the ChadOx-1 presented not only a better antibody response but also a significant modulation in the percentage of T cell profiles, mainly in the previously exercised group.

Reactivation of varicella zoster infection presenting as acute retinal necrosis post COVID 19 vaccination in an Asian Indian male

PURPOSE

To present the clinical features of a rare case of varicella zoster infection following one dose of Coronavirus Disease 2019 (COVID-19) vaccination in an elderly Asian Indian male.

METHODS

Retrospective observational case report.

RESULTS

A 71-year-old gentleman presented to us with complaints of reduced vision associated with redness and pain in his right eye for 1 week. On examination he revealed a right eye pan uveitis picture with circumcorneal congestion, multiple fine keratic precipitates, anterior chamber cells and flare, vitritis and widespread areas of acute retinal necrosis. His left eye was within normal limits. Ten days prior to the presentation he had received the first dose of COVID-19 vaccine following which he had developed fever for 2 days that preceded the red eye. The patient's aqueous sample tested positive for varicella zoster virus (VZV) by nested polymerase chain reaction (PCR) method. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in reverse transcriptase polymerase chain reaction (RT-PCR) assay from the aqueous and also from the nasopharyngeal swab was negative.

CONCLUSION AND SIGNIFICANCE

To the best of our knowledge this is the earliest description of a case that has a viral reactivation following COVID-19 vaccination. Elderly people with pre-existing comorbidities, may be at a risk of both primary coronavirus infection and unconceivable risk of aberrant immune reactions leading to a different virus infection or reactivation need to be kept in mind. We present a possible link between SARS-CoV-2 virus vaccination and varicella zoster reactivation in this patient.

Sex-Differential and Non-specific Effects of Vaccines Over the Life Course

Biological sex and age have profound effects on immune responses throughout the lifespan and impact vaccine acceptance, responses, and outcomes. Mounting evidence from epidemiological, clinical, and animal model studies show that males and females respond differentially to vaccination throughout the lifespan. Within age groups, females tend to produce greater vaccine-induced immune responses than males, with sex differences apparent across all age groups, but are most pronounced among reproductive aged individuals. Females report more adverse effects following vaccination than males. Females, especially among children under 5 years of age, also experience more non-specific effects of vaccination. Despite these known sex- and age-specific differences in vaccine-induced immune responses and outcomes, sex and age are often ignored in vaccine research. Herein, we review the known sex differences in the immunogenicity, effectiveness, reactogenicity, and non-specific effects of vaccination over the lifespan. Ways in which these data can be leveraged to improve vaccine research are described.

Efficacy and Safety of COVID-19 Vaccination in Older Adults: A Systematic Review and Meta-Analysis

Objective: To analyze the differences in efficacy and safety of different types of novel coronavirus pneumonia (COVID-19) vaccines in different age groups (young adults and elderly). Methods: Randomized controlled trials (RCTs) on COVID-19 vaccine in PubMed, Embase, Web of Science, and Cochrane library were searched by computer, and eight eligible studies were analyzed. Meta-analysis was performed using Stata 16.0 and RevMan5.4 software. Results: The mean geometric titer (GMT) of the virus in the elderly was significantly higher than that in the placebo group (SMD = 0.91, 95% CI (0.68, 1.15), p < 0.01), presenting no obvious difference compared with the young adults (SMD = 0.19, 95% CI (0.38, 0.01), p = 0.06). Meanwhile, the effect of multiple vaccinations was better than that of single vaccination (SMD = 0.83, 95% CI (0.33, 1.34), p < 0.01). However, the number of adverse events (AEs) in the elderly was lower than that in the young adults (OR = 0.35, 95% CI (0.29, 0.42), p < 0.01). Conclusions: The immunization effect of COVID-19 vaccine in the elderly is obvious, especially after multiple vaccinations, and the incidence of AEs in the elderly is low, which proves that the vaccination of the elderly is safe and effective.

The correlation between serum 25-hydroxy-vitamin D levels and anti-SARS-CoV-2 S-RBD IgG and neutralizing antibody levels among cancer patients receiving COVID-19 vaccines

Introduction

During the coronavirus disease 2019 (COVID-19) pandemic, vitamin D has been established as an immune-modulator that reduces pro-inflammatory damage which effectively diminish the severity of COVID-19. Vitamin D also has a significant effect against influenza and dengue and increase the seroconversion following influenza vaccination. To date, the role of vitamin D in optimizing the efficacy of COVID-19 vaccines remains unclear. This study aimed to analyze the correlation between serum 25-hydroxy-cholecalciferol or 25(OH)D levels and anti-SARS-CoV-2 S-RBD IgG and neutralizing antibody levels among cancer patients.

Methodology

A multicenter cross-sectional study was conducted among solid and hematologic cancer patients who were vaccinated with two doses of the same types of COVID-19 vaccines (either mRNA, non-replicating viral vector, or inactivated) within 6 months.

Result

The median serum 25(OH)D level in 119 cancer patients was 36.36 [IQR = 30.30] ng/mL. The seropositivity of S-RBD IgG and NAb reached 93.3 and 94.1%, respectively. The S-RBD IgG level was significantly higher in the sufficient group (median = 414.07 [1,441.83] AU/mL) than in the deficient group (median = 91.56 [652.00] AU/mL) (p-value = 0.049). Among non-chemotherapy subjects, the anti-SARS-CoV-2 S-RBD IgG levels had a significant positive correlation with 25(OH)D levels (p-value = 0.03; R = 0.588). The NAb levels also showed significantly positive correlation with 25(OH)D level (p-value = 0.005; R = 0.561). The 25(OH)D levels were positively correlated with S-RBD IgG levels among subjects younger than 60 years old (p-value = 0.047; R = 0.136). However, serum 25 (OH)D levels showed no such correlation with S-RBD IgG levels among subjects older than 60 years old (p-value = 0.933; R = 0.136).

Conclusion

Both anti-SARS-CoV-2 S-RBD IgG and NAb levels developed moderate correlation with 25(OH)D levels among subjects treated without chemotherapy. The S-RBD IgG levels also had positive correlation with 25(OH)D levels among subjects younger than 60 years old. Thus, we recommended cancer patients to maintain serum 25(OH)D levels above 30 ng/mL (75 nmol/L) to enhance the efficacy of COVID-19 vaccines.

Drivers of and barriers to routine adult vaccination: A systematic literature review

We performed a systematic literature review in PubMed and Embase (2016-2021) to investigate the drivers of and barriers to routine vaccination in adults aged 50 and older globally. A thematic assessment identified three categories across 61 publications: sociodemographic, health-related, and attitudinal. The most common sociodemographic determinants (factors identified in studies; n = 47) associated with vaccination uptake were economic status, age, education, and household composition, which had mixed effects on vaccine uptake. For health-related determinants (n = 27), individuals with comorbidities and health care consumption were the most common factors, both increased vaccine uptake. The most common attitudinal factors (n = 42) were self-efficacy, provider or other's recommendations, and vaccine-preventable disease awareness; across studies, all attitude factors had a positive effect, unlike the sociodemographic and health status categories. Findings suggest that patient and provider awareness and education campaigns are effective ways to increase uptake of routine vaccinations in older adults.

DYNAMIC cohort study evaluating metabolic predictors of influenza vaccine immune response in older adults

Immunosenescence (age-related immune dysfunction) and inflamm-aging contribute to suboptimal immune responses in older adults to standard-dose influenza vaccines, which may be exacerbated in those with metabolic co-morbidities. We sought to investigate metabolic factors/predictors of influenza vaccine immune response in an older adult (age ≥65 years) cohort in Singapore, where influenza typically circulates year-round. The primary outcome for the DYNAMIC prospective cohort study was haemagglutination-inhibition titer (HAI) response to each of the trivalent inactivated influenza vaccine strains at day 28 (D28) compared to baseline (D0), as assessed by seroconversion and D28/D0 log2 HAI fold rise. Baseline blood samples were tested for total Vitamin D (25-(OH) D) levels. We enrolled 234 participants in June-Dec 2017. Two hundred twenty completed all study visits. The median age was 71 [IQR 68-75] years, 67 (30.5%) had diabetes mellitus (DM), and the median BMI was 24.9 [IQR 22.2-27.8] kg/m². Median baseline totals 25-(OH) D was 29 [IQR: 21-29] ng/ml. Age, DM, obesity, and baseline 25-(OH) D were not associated with HAI fold rise in multivariable analysis. More recent prior influenza vaccination and higher baseline HAI titers were associated with lower HAI fold rise for influenza A/HK/H3N2. Physical activity was associated with a higher HAI fold rise for influenza A/HK/H3N2 in a dose-response relationship (p-test for trend = 0.015). Older adults with well-controlled metabolic co-morbidities retain HAI response to the influenza vaccine, and physical activity had a beneficial effect on immune response, particularly for influenza A/HK/H3N2.

How Can We Improve the Vaccination Response in Older People? Part II: Targeting Immunosenescence of Adaptive Immunity Cells

The number of people that are 65 years old or older has been increasing due to the improvement in medicine and public health. However, this trend is not accompanied by an increase in quality of life, and this population is vulnerable to most illnesses, especially to infectious diseases. Vaccination is the best strategy to prevent this fact, but older people present a less efficient response, as their immune system is weaker due mainly to a phenomenon known as immunosenescence. The adaptive immune system is constituted by two types of lymphocytes, T and B cells, and the function and fitness of these cell populations are affected during ageing. Here, we review the impact of ageing on T and B cells and discuss the approaches that have been described or proposed to modulate and reverse the decline of the ageing adaptive immune system.

An Economic Evaluation of the Adjuvanted Quadrivalent Influenza Vaccine Compared with Standard-Dose Quadrivalent Influenza Vaccine in the Spanish Older Adult Population

Standard-dose quadrivalent influenza vaccines (QIV) are designed to provide protection against all four influenza strains. Adjuvanted QIV (aQIV), indicated for individuals aged 65+ years, combines MF59^® adjuvant (an oil-in-water emulsion of squalene oil) with a standard dose of antigen, and is designed to produce stronger and longer immune response, especially in the elderly where immunosenescence reduces vaccine effectiveness. This study evaluated the cost-effectiveness of aQIV vs. egg-based standard-dose QIV (QIVe) in the elderly population, from the payer and societal perspective in Spain. A dynamic transmission model, which accounts for herd protection, was used to predict the number of medically attended infections in Spain. A decision tree structure was used to forecast influenza-related costs and benefits. Influenza-related probabilities of outpatient visit, hospitalization, work absenteeism, mortality, and associated utilities and costs were extracted from Spanish and European published literature. Relative vaccine effectiveness (rVE) was sourced from two different meta-analyses: the first meta-analysis was informed by laboratory-confirmed influenza studies only, resulting in a rVE = 34.6% (CI95% 2-66%) in favor of aQIV; the second meta-analysis included real world evidence influenza-related medical encounters outcomes, resulting in a rVE = 13.9% (CI95% 4.2-23.5%) in benefit of aQIV. All costs were expressed in 2021 euros. Results indicate that replacing QIVe with aQIV in the Spanish elderly population would prevent on average 43,664 influenza complicated cases, 1111 hospitalizations, and 569 deaths (with a rVE = 34.6%) or 19,104 influenza complicated cases, 486 hospitalizations, and 252 deaths (with a rVE = 13.9%). When the rVE of aQIV vs. QIVe is 34.6%, the incremental cost per quality adjusted life years (QALY) gained was €2240 from the payer; from the societal perspective, aQIV was cost saving compared with QIVe. If the rVE was 13.9%, the incremental cost per QALY was €6694 and €3936 from the payer and societal perspective, respectively. Sensitivity analyses validated the robustness of these findings. Results indicate that replacing QIVe with aQIV in the Spanish elderly population is a cost-effective strategy for the Spanish healthcare system.

Analysis of Viral and Host Factors on Immunogenicity of 2018, 2019, and 2020 Southern Hemisphere Seasonal Trivalent Inactivated Influenza Vaccine in Adults in Brazil

Annual vaccination against influenza is the best tool to prevent deaths and hospitalizations. Regular updates of trivalent inactivated influenza vaccines (TIV) are necessary due to high mutation rates in influenza viruses. TIV effectiveness is affected by antigenic mismatches, age, previous immunity, and other host factors. Studying TIV effectiveness annually in different populations is critical. The serological responses to Southern-Hemisphere TIV and circulating influenza strains were evaluated in 2018−2020 among Brazilian volunteers, using hemagglutination inhibition (HI) assays. Post-vaccination titers were corrected to account for pre-vaccination titers. Our population achieved >83% post-vaccination seroprotection levels, whereas seroconversion rates ranged from 10% to 46%. TIV significantly enhanced antibody titers and seroprotection against all prior and contemporary vaccine and circulating strains tested. Strong cross-reactive responses were detected, especially between H1N1 subtypes. A/Singapore/INFIMH-16-0019/2016, included in the 2018 TIV, induced the poorest response. Significant titer and seroprotection reductions were observed 6 and 12 months after vaccination. Age had a slight effect on TIV response, whereas previous vaccination was associated with lower seroconversion rates and titers. Despite this, TIV induced high seroprotection for all strains, in all groups. Regular TIV evaluations, based on regional influenza strain circulation, should be conducted and the factors affecting response studied.

Antibody Response in Healthcare Workers before and after the Third Dose of Anti-SARS-CoV-2 Vaccine: A Pilot Study

The SARS-CoV-2 pandemic led to the development of various vaccines. The BNT162b2 mRNA vaccine was the first approved due to its efficacy in eliciting a humoral immunity response after the second dose. However, a decrease in the antibody concentration was observed over time. Therefore, the administration of a third dose was scheduled, primarily for frail people and workers of essential public activities. The aim of this study was to assess the level of antibodies against the spike (S) RBD of SARS-CoV-2 in healthcare workers before and after the third dose of BNT162b2 vaccine, according to sex, age, and the time interval between vaccine doses and tests. All 37 (12 males, 25 females, 19 < 50 years old, 18 ≥ 50 years old) healthcare workers recruited showed a consistent antibody titer increase after the third dose. Data analysis showed that the antibody concentration before the third dose significantly decreased as the time interval up to the test increased, and a significantly higher level was shown in young than older people. Cluster analysis revealed that young females had a higher antibody level than older females before the third dose (p < 0.05). This study indicated the benefit of the third dose of BNT162b2 vaccine and its effect on leveling up the humoral immune response.

Influenza Viruses and Vaccines: The Role of Vaccine Effectiveness Studies for Evaluation of the Benefits of Influenza Vaccines

Influenza is a vaccine preventable disease and vaccination remains the most effective method of controlling the morbidity and mortality of seasonal influenza, especially with respect to risk groups. To date, three types of influenza vaccines have been licensed: inactivated, live-attenuated, and recombinant haemagglutinin vaccines. Effectiveness studies allow an assessment of the positive effects of influenza vaccines in the field. The effectiveness of current influenza is suboptimal, being estimated as 40% to 60% when the vaccines strains are antigenically well-matched with the circulating viruses. This review focuses on influenza viruses and vaccines and the role of vaccine effectiveness studies for evaluating the benefits of influenza vaccines. Overall, influenza vaccines are effective against morbidity and mortality in all age and risk groups, especially in young children and older adults. However, the effectiveness is dependent on several factors such as the age of vaccinees, the match between the strain included in the vaccine composition and the circulating virus, egg-adaptations occurring during the production process, and the subject’s history of previous vaccination.

Reduced T Cell and Antibody Responses to Inactivated Coronavirus Vaccine Among Individuals Above 55 Years Old

CoronaVac is an inactivated SARS-CoV-2 vaccine that has been rolled out in several low and middle-income countries including Brazil, where it was the mainstay of the first wave of immunization of healthcare workers and the elderly population. We aimed to assess the T cell and antibody responses of vaccinated individuals as compared to convalescent patients. We detected IgG against SARS-CoV-2 antigens, neutralizing antibodies against the reference Wuhan SARS-CoV-2 strain and used SARS-CoV-2 peptides to detect IFN-g and IL-2 specific T cell responses in a group of CoronaVac vaccinated individuals (N = 101) and convalescent (N = 72) individuals. The frequency among vaccinated individuals, of whom 96% displayed T cell and/or antibody responses to SARS-CoV-2, is comparable to 98.5% responses of convalescent individuals. We observed that among vaccinated individuals, men and individuals 55 years or older developed significantly lower anti-RBD, anti-NP and neutralization titers against the Wuhan strain and antigen-induced IL-2 production by T cells. Neutralizing antibody responses for Gamma variant were even lower than for the Wuhan strain. Even though some studies indicated CoronaVac helped reduce mortality among elderly people, considering the appearance of novel variants of concern, CoronaVac vaccinated individuals above 55 years old are likely to benefit from a heterologous third dose/booster vaccine to increase immune response and likely protection.

Vaccine strain affects seroconversion after influenza vaccination in COPD patients and healthy older people

Though clinical guidelines recommend influenza vaccination for chronic obstructive pulmonary disease (COPD) patients and other high-risk populations, it is unclear whether current vaccination strategies induce optimal antibody responses. This study aimed to identify key variables associated with strain-specific antibody responses in COPD patients and healthy older people. 76 COPD and 72 healthy participants were recruited from two Australian centres and inoculated with influenza vaccine. Serum strain-specific antibody titres were measured pre- and post-inoculation. Seroconversion rate was the primary endpoint. Antibody responses varied between vaccine strains. The highest rates of seroconversion were seen with novel strains (36-55%), with lesser responses to strains included in the vaccine in more than one consecutive year (27-33%). Vaccine responses were similar in COPD patients and healthy participants. Vaccine strain, hypertension and latitude were independent predictors of seroconversion. Our findings reassure that influenza vaccination is equally immunogenic in COPD patients and healthy older people; however, there is room for improvement. There may be a need to personalise the yearly influenza vaccine, including consideration of pre-existing antibody titres, in order to target gaps in individual antibody repertoires and improve protection.

An exploratory study to assess patterns of influenza- and pneumonia-related mortality among the Italian elderly

Older adults are at disproportionately high risk of severe influenza-related outcomes and represent the main target of the annual influenza vaccination. The protective effect of seasonal influenza vaccination on the observed mortality indicators is controversial. In this ecological study, spatiotemporal patterns of pneumonia- and influenza-related mortality registered in the Italian elderly over seven (2011–2017) consecutive seasons were explored and the epidemiological association between the observed local pneumonia- and influenza-related mortality and influenza vaccination campaign features were modeled by using both fixed- and random-effects panel regression models. The descriptive spatiotemporal analysis showed a clear North–South gradient, where northern regions tended to report more pneumonia- and influenza-related deaths. After adjustment for potential confounders, it was found that each 1% increase in influenza vaccination coverage rate would be associated (P < .001) with a 1.6–1.9% decrease in pneumonia- and influenza-related mortality. Moreover, each 1% increase in the use of MF59®-adjuvanted trivalent influenza vaccine would be associated (P < .05) with a further 0.4% decrease in pneumonia- and influenza-related mortality. This study supports the increase in annual influenza vaccination in Italy and suggests that a higher level of use of the adjuvanted influenza vaccine in the elderly may be beneficial.

AZD1222/ChAdOx1 nCoV-19 vaccination induces a polyfunctional spike protein-specific TH1 response with a diverse TCR repertoire

AZD1222 (ChAdOx1 nCoV-19), a replication-deficient simian adenovirus–vectored vaccine, has demonstrated safety, efficacy, and immunogenicity against coronavirus disease 2019 in clinical trials and real-world studies. We characterized CD4+ and CD8+ T cell responses induced by AZD1222 vaccination in peripheral blood mononuclear cells from 296 unique vaccine recipients aged 18 to 85 years who enrolled in the phase 2/3 COV002 trial. Total spike protein–specific CD4+ T cell helper type 1 (TH1) and CD8+ T cell responses were increased in AZD1222-vaccinated adults of all ages after two doses of AZD1222. CD4+ TH2 responses after AZD1222 vaccination were not detected. Furthermore, AZD1222-specific TH1 and CD8+ T cells both displayed a high degree of polyfunctionality in all adult age groups. T cell receptor β (TCRβ) sequences from vaccinated participants mapped against TCR sequences known to react to SARS-CoV-2 revealed substantial breadth and depth across the SARS-CoV-2 spike protein for both AZD1222-induced CD4+ and CD8+ T cell responses. Overall, AZD1222 vaccination induced a polyfunctional TH1-dominated T cell response, with broad CD4+ and CD8+ T cell coverage across the SARS-CoV-2 spike protein.

Antiviral Gene Expression in Young and Aged Murine Lung during H1N1 and H3N2

Influenza is a respiratory virus that alone or in combination with secondary bacterial pathogens can contribute to the development of acute pneumonia in persons >65 years of age. Host innate immune antiviral signaling early in response to influenza is essential to inhibit early viral replication and guide the initiation of adaptive immune responses. Using young adult (3 months) and aged adult mice infected with mouse adapted H1N1 or H3N2, the results of our study illustrate dysregulated and/or diminished activation of key signaling pathways in aged lung contribute to increased lung inflammation and morbidity. Specifically, within the first seven days of infection, there were significant changes in genes associated with TLR and RIG-I signaling detected in aged murine lung in response to H1N1 or H3N2. Taken together, the results of our study expand our current understanding of age-associated changes in antiviral signaling in the lung.

Effectiveness of the MF59-adjuvanted trivalent or quadrivalent seasonal influenza vaccine among adults 65 years of age or older, a systematic review and meta-analysis

BACKGROUND

Standard-dose seasonal influenza vaccines often produce modest immunogenic responses in adults ≥65 years old. MF59 is intended to elicit a greater magnitude and increased breadth of immune response.

OBJECTIVE

To determine the effectiveness of seasonal MF59-adjuvanted trivalent/quadrivalent influenza vaccine (aTIV/aQIV) relative to no vaccination or vaccination with standard or high-dose egg-based influenza vaccines among people ≥65 years old.

METHODS

Cochrane methodological standards and PRISMA-P guidelines were followed. Real-world evidence from non-interventional studies published in peer-reviewed journals and gray literature from 1997 through to July 15, 2020, including cluster-randomized trials, were eligible. Two reviewers independently extracted data; risk of bias was assessed using the ROBINS-I tool.

RESULTS

Twenty-one studies conducted during the 2006/07-2019/20 influenza seasons were included in the qualitative review; 16 in the meta-analyses. Meta-analysis of test-negative studies found that aTIV reduced medical encounters due to lab-confirmed influenza with pooled estimates of 40.7% (95% CI: 21.9, 54.9; I2  = 0%) for non-emergency outpatient visits and 58.5% (40.7, 70.9; I2  = 52.9%) for hospitalized patients. The pooled estimate of VE from case-control studies was 51.3% (39.1, 61.1; I2  = 0%) against influenza- or pneumonia-related hospitalization. The pooled estimates for the relative VE of aTIV for the prevention of influenza-related medical encounters were 13.9% (4.2, 23.5; I2  = 95.9%) compared with TIV, 13.7% (3.1, 24.2; I2  = 98.8%) compared with QIV, and 2.8% (-2.9, 8.5; I2  = 94.5%) compared with HD-TIV.

CONCLUSIONS

Among adults ≥65 years, aTIV demonstrated significant absolute VE, improved relative VE compared to non-adjuvanted standard-dose TIV/QIV, and comparable relative VE to high-dose TIV.

Drug delivery systems as immunomodulators for therapy of infectious disease: Relevance to COVID-19

The emergence of SARS-CoV-2, and the ensuing global pandemic, has resulted in an unprecedented response to identify therapies that can limit uncontrolled inflammation observed in patients with moderate to severe COVID-19. The immune pathology behind COVID-19 is complex and involves the activation and interaction of multiple systems including, but not limited to, complement, inflammasomes, endothelial as well as innate and adaptive immune cells to bring about a convoluted profile of inflammation, coagulation and tissue damage. To date, therapeutic approaches have focussed on inhibition of coagulation, untargeted immune suppression and/or cytokine-directed blocking agents. Regardless of recently achieved improvements in individual patient outcomes and survival rates, improved and focussed approaches targeting individual systems involved is needed to further improve prognosis and wellbeing. This review summarizes the current understanding of molecular and cellular systems involved in the pathophysiology of COVID-19, and their contribution to pathogen clearance and damage to then discuss possible therapeutic options involving immunomodulatory drug delivery systems as well as summarising the complex interplay between them.

Better, Faster, Stronger: mRNA Vaccines Show Promise for Influenza Vaccination in Older Adults

Older adults have diminished immune responses that lead to increased susceptibility and severity of infectious diseases. Influenza is a leading killer of older adults despite the availability of seasonal influenza vaccination. Influenza vaccines are strain specific, and their efficacy varies greatly year to year based on how well the vaccine virus matches the circulating strains. Additionally, older adults have reduced vaccination responses. The COVID-19 pandemic highlighted the increased mortality rate in older adults for infectious disease, and brought vaccine development to the forefront. The speed of vaccine development was met with an equally impressive vaccine efficacy. Interestingly, both mRNA-based COVID-19 vaccines currently available have shown similar efficacy in both young and older adults. mRNA vaccine production has significantly reduced the production timeline compared to current influenza vaccines, making them particularly attractive for influenza vaccine development. Faster production coupled with improved efficacy would be a tremendous advancement in protecting older adults from influenza morbidity and mortality.

Current concepts on communication between the central nervous system and peripheral immunity via lymphatics: what roles do lymphatics play in brain and spinal cord disease pathogenesis?

The central nervous system (CNS) lacks conventional lymphatics within the CNS parenchyma, yet still maintains fluid homeostasis and immunosurveillance. How the CNS communicates with systemic immunity has thus been a topic of interest for scientists in the past century, which has led to several theories of CNS drainage routes. In addition to perineural routes, rediscoveries of lymphatics surrounding the CNS in the meninges revealed an extensive network of lymphatics, which we now know play a significant role in fluid homeostasis and immunosurveillance. These meningeal lymphatic networks exist along the superior sagittal sinus and transverse sinus dorsal to the brain, near the cribriform plate below the olfactory bulbs, at the base of the brain, and surrounding the spinal cord. Inhibition of one or all of these lymphatic networks can reduce CNS autoimmunity in a mouse model of multiple sclerosis (MS), while augmenting these lymphatic networks can improve immunosurveillance, immunotherapy, and clearance in glioblastoma, Alzheimer's disease, traumatic brain injury, and cerebrovascular injury. In this review, we will provide historical context of how CNS drainage contributes to immune surveillance, how more recently published studies fit meningeal lymphatics into the context of CNS homeostasis and neuroinflammation, identify the complex dualities of lymphatic function during neuroinflammation and how therapeutics targeting lymphatic function may be more complicated than currently appreciated, and conclude by identifying some unresolved questions and controversies that may guide future research.

Evaluation of Next-Generation H3 Influenza Vaccines in Ferrets Pre-Immune to Historical H3N2 Viruses

Each person has a unique immune history to past influenza virus infections. Exposure to influenza viruses early in life establishes memory B cell populations that influence future immune responses to influenza vaccination. Current influenza vaccines elicit antibodies that are typically strain specific and do not offer broad protection against antigenically drifted influenza strains in all age groups of people. This is particularly true for vaccine antigens of the A(H3N2) influenza virus subtype, where continual antigenic drift necessitates frequent vaccine reformulation. Broadly-reactive influenza virus vaccine antigens offer a solution to combat antigenic drift, but they also need to be equally effective in all populations, regardless of prior influenza virus exposure history. This study examined the role that pre-existing immunity plays on influenza virus vaccination. Ferrets were infected with historical A(H3N2) influenza viruses isolated from either the 1970’s, 1980’s, or 1990’s and then vaccinated with computationally optimized broadly reactive antigens (COBRA) or wild-type (WT) influenza virus like particles (VLPs) expressing hemagglutinin (HA) vaccine antigens to examine the expansion of immune breadth. Vaccines with the H3 COBRA HA antigens had more cross-reactive antibodies following a single vaccination in all three pre-immune regimens than vaccines with WT H3 HA antigens against historical, contemporary, and future drifted A(H3N2) influenza viruses. The H3 COBRA HA vaccines also induced antibodies capable of neutralizing live virus infections against modern drifted A(H3N2) strains at higher titers than the WT H3 HA vaccine comparators.

Prevalence of antibodies against seasonal influenza A and B viruses among older adults in rural Thailand: A cross-sectional study

Assessing the seroprevalence of the high-risk individuals against the influenza virus is essential to evaluate the progress of vaccine implementation programs and establish influenza virus interventions. Herein, we identified the pre-existing cross-protection of the circulating seasonal influenza viruses among the older-aged population. A cross-sectional study was performed base on the 176 residual sera samples collected from older adults aged 60 to 95 years without a history of vaccination in rural Thailand in 2015. Sera antibody titers against influenza A and B viruses circulating between 2016 and 2019 were determined by hemagglutination inhibition assay. These findings indicated the low titers of pre-existing antibodies to circulating influenza subtypes and showed age-independent antibody titers among the old adults. Moderate seropositive rates (HAI ≥ 1:40) were observed in influenza A viruses (65.9%A(H3N2), 50.0% for A(H1N1) pdm09), and found comparatively lower rates in influenza B viruses (14% B/Yam2, 21% B/Yam3 and 25% B/Vic). Only 5% of individuals possessed broadly protective antibodies against both seasonal influenza A and B virus in this region. Our findings highlighted the low pre-existing antibodies to circulating influenza strains in the following season observed in older adults. The serological study will help inform policy-makers for health care planning and guide control measures concerning vaccination programs.

T-cell mediated immunity after AZD1222 vaccination: A polyfunctional spike-specific Th1 response with a diverse TCR repertoire

AZD1222 (ChAdOx1 nCoV-19), a replication-deficient simian adenovirus-vectored vaccine, has demonstrated safety, efficacy, and immunogenicity against coronavirus disease 2019 (COVID-19) in clinical trials and real-world studies. We characterized CD4+ and CD8+ T-cell responses induced by AZD1222 vaccination in peripheral blood mononuclear cells (PBMCs) from 280 unique vaccine recipients aged 18-85 years who enrolled in the phase 2/3 COV002 trial. Total spike-specific CD4+ T cell helper type 1 (Th1) and CD8+ T-cell responses were significantly increased in AZD1222-vaccinated adults of all ages following two doses of AZD1222. CD4+ Th2 responses following AZD1222 vaccination were not detected. Furthermore, AZD1222-specific Th1 and CD8+ T cells both displayed a high degree of polyfunctionality in all adult age groups. T-cell receptor (TCR) β sequences from vaccinated participants mapped against TCR sequences known to react to SARS-CoV-2 revealed substantial breadth and depth across the SARS-CoV-2 spike protein for the AZD1222-induced CD4+ and CD8+ T-cell responses. Overall, AZD1222 vaccination induced a robust, polyfunctional Th1-dominated T-cell response, with broad CD4+ and CD8+ T-cell coverage across the SARS-CoV-2 spike protein.

One Sentence Summary

Polyfunctional CD4+ and CD8+ T-cell responses are elicited against the SARS-CoV-2 spike protein following vaccination with AZD1222.

Non-EPI Vaccine Hesitancy among Chinese Adults: A Cross-Sectional Study

Vaccination against coronavirus disease 2019 (COVID-19) is paramount to curtailing the pandemic. However, the impact of the Non-Expanded Program on Immunization (non-EPI) and COVID-19 vaccine hesitancy on vaccine uptake among Chinese adults remain unclear. This study was an online survey performed in Eastern, Central, and Western China between February 2021 and March 2021 using proportional sampling (n = 7381). Adults aged ≥ 18 years were included, especially younger people (aged < 65). Vaccine hesitancy was assessed using the 3C model and relative scales; logistic regression was used to explore the factors affecting vaccination uptake; structural equation modeling was used to evaluate the correlations between variables. Overall, 67.6% and 24.7% of adults reported vaccine hesitancy toward the non-EPI and COVID-19 vaccines, respectively. Participants (66.3%) reported taking the vaccine mainly based on recommendations from medical staff. Vaccine-hesitant participants (60.5%) reported a fear of side effects as the deciding factor in vaccine rejection. Vaccine hesitancy interacted negatively with confidence (β = −0.349, p < 0.001) and convenience (β = −0.232, p < 0.001), and positively with complacence (β = 0.838, p < 0.001). Nonmedical personnel, adults who had previously received the influenza vaccine, and older people had lower vaccine hesitancy than their counterparts. Most Chinese adults have non-EPI but not COVID-19 vaccine hesitancy. Vaccine safety remains a concern.