Background and Objectives:
Influenza vaccination is vital for healthy aging, yet coverage among older adults remains below the WHO’s 75% target in many countries. The WHO’s Behavioral and Social Drivers (BeSD) framework offers a comprehensive lens to identify factors influencing vaccine uptake: thinking and feeling, social processes, motivation, and practical issues. This scoping review synthesizes current evidence on these drivers among adults aged 60 and older to inform interventions aimed at boosting vaccine coverage.
Methods:
Following Arksey and O’Malley’s framework and PRISMA-ScR, we searched MEDLINE, EMBASE, Web of Science, CINAHL, and Cochrane for studies published before December 31, 2024. We identified 46 studies (1999–2024) from 20 countries, mostly quantitative (n=40), along with 4 qualitative and 2 mixed-methods. Sample sizes ranged from 15 to 724,276 participants, reflecting diverse healthcare contexts and influenza patterns.
Results:
Six key themes emerged under the BeSD framework. Socio-Demographic Factors (gender, age, and living environment) showed inconsistent influences on vaccination, though large-scale studies highlighted the importance of socioeconomic status. Health and Medical Factors, including chronic conditions, prior vaccination, and healthcare interactions, generally facilitated uptake, while frailty and comorbidities sometimes posed barriers. Thinking and Feeling—notably high perceived influenza risk and strong vaccine confidence—promoted acceptance; however, fear of adverse effects and doubts about efficacy impeded it. Social Processes, such as encouragement from family and healthcare providers, aided vaccination, while misinformation and low institutional trust undermined it. In addition to vaccination intention and vaccine hesitancy, self-efficacy, certainty and herd mentality of decision-making can also influence vaccination motivation. Finally, Practical Issues (cost, limited access, and language barriers, especially in rural areas) were frequent obstacles to obtaining the vaccine.
Conclusions:
By mapping these themes within BeSD domains, our review underscores how multifaceted drivers—spanning belief systems, social influence, and practical obstacles—converge to shape vaccination decisions. Tailored, evidence-based strategies addressing these drivers are crucial for raising influenza vaccination rates and promoting healthier aging.

We estimated the effectiveness of standard-dose influenza vaccine in preventing hospitalisation for cardiovascular disease (CVD) among New South Wales (NSW) residents aged ≥50 years in Australia during 2017, which was a severe A/H3N2 season.
We conducted a nested matched case-control study within the 45 and Up cohort study, linking data from the Australian Immunization Register, NSW Admitted Patient Data Collection and Pharmaceutical Benefits Schedule. Cases were individuals hospitalised for CVD (ICD-10 AM I00-I99) and controls were those hospitalised for gastrointestinal diseases (ICD-10 AM K00-K93). We balanced them using 1:1 propensity score matching based on age group (50-64, 65-74, 75-84, ≥85 years) and sex. After adjusting for confounders (smoking, body mass index and income), we calculated the adjusted odds ratio (aOR) for vaccination during the peak season using multivariable logistic regression. E-values were estimated to assess residual confounding. Vaccine effectiveness (VE) was calculated as (1─aOR) x 100.
There were 10,445 (4,452 cases and 5,993 controls) study participants. Following matching, 8,904 (85.2%) were identified (58.3% males, mean age of 76.4 ± 10.4 years). Following adjustment for confounders, the aOR of averting a CVD hospitalization was 0.15 (95% CI: 0.13 to 0.17; P <0.001). The estimated VE against CVD hospitalization was 85% (95% CI: 83 to 87). We found an E-value of 12.82, indicating strong evidence of minimal residual confounding.
In the severe 2017 influenza A/H3N2 season in Australia, we observed a high VE in preventing cardiovascular hospitalization despite low VE against influenza infection prevention. Improving vaccine uptake may reduce cardiovascular burden.

BACKGROUND: Respiratory tract infections may trigger acute myocardial infarction (AMI) and stroke. However, the pathogen-specific relative contributions and overall public health impact are less clear. We conducted a systematic review to examine the relative effects of laboratory-confirmed respiratory virus infections as triggers for AMI and stroke.

METHODS: We searched MEDLINE, PubMed, Embase, Cochrane, and Web of Science, from inception to August 2024. Analytic epidemiological studies among human participants, published in any language, capturing laboratory-confirmatory respiratory viral infection(s) and that reported AMI or stroke outcomes, were eligible. Data were analysed by exposure-outcome relationship and reported measure of effect(s) and between-study heterogeneity (I²) assessed. If studies were sufficiently homogeneous, data were pooled in a random effects model. Risk of bias was assessed across studies and certainty of the evidence graded. This review was registered with PROSPERO: CRD42024494997.

RESULTS: Of 11,017 articles identified, 48 studies were included. SARS-CoV-2 and influenza were the most frequently associated triggers. There was high-certainty evidence that influenza triggers AMI (incidence rate ratio (IRR): 5.37; 95% CI, 3.48-8.28; I² = 69.4%). SARS-CoV-2, respiratory syncytial virus, and Coxsackie B virus infection may also trigger AMI, albeit with lower certainty of evidence. Influenza was associated with a 4.7-fold increased risk of stroke within the first 28 days following infection (IRR: 4.72; 95% CI: 3.78-5.90; I² = 0%). Moderate-level evidence suggested SARS-CoV-2 and cytomegalovirus (CMV) may trigger stroke. As no randomised controlled trials met inclusion criteria, this review was limited entirely to observational studies, hence subject to risk of bias due to confounding.

CONCLUSION: Our findings suggest that common, often vaccine-preventable, respiratory viral infections are associated with an increased short-term risk of AMI and stroke. Vaccine probe studies, specific to influenza and SARS-CoV-2, for the prevention of acute cardiovascular events may be helpful to assess the impact on population burden.

Background: Influenza vaccine coverage has been persistently suboptimal in Australian adults. By the end of the 2024 influenza season, the country saw its lowest annual coverage rates compared to the preceding five-year period. While past influenza vaccination is a strong predictor of current uptake, vaccination behaviour can be inconsistent, contributing to patchy coverage. The National Vaccination Insights Project sought to understand the barriers and drivers of routine annual influenza vaccine uptake in Australian adults.

Methods: Between July and September 2024, eighteen in-depth interviews were conducted with adults aged over 18 years who did not intend to receive an influenza vaccine in 2024 but had received at least one in the preceding two years. Transcripts were analysed using the framework method.

Results: For most interviewees, not getting an influenza vaccine was their default behaviour. At busy times, vaccination was not prioritised, and inaction was more convenient, especially when they were not worried about getting influenza or felt unsupported by entities that encourage vaccination (i.e. governments and the medical establishment). At times when they had received an influenza vaccine, interviewees acted in response to opportunities and prompts that offered convenient avenues for vaccination rather than actively seeking it out themselves. Other drivers included; the perceived importance of preventing illness during a life event such as travel or pregnancy; and the perceived responsibility to protect close others from influenza.

Conclusions: To encourage annual influenza vaccine uptake amongst Australian adults, increasing available information about influenza severity and encouraging vaccination via personalised annual prompts may be useful. Consideration should also be given to improving experiences within health settings by adequately addressing concerns and mitigating distress. Increased access to vaccination during people’s regular routine, for example, in workplaces, and engaging community groups with vaccination may also help normalise, and reinforce the importance of, annual influenza vaccination.

Aim : High-dose quadrivalent influenza vaccine (QIV-HD) has been shown to be more effective than standard-dose (QIV-SD) in reducing influenza infection, but whether diabetes status affects relative vaccine effectiveness (rVE) is unknown. We aimed to assess rVE on change in glycated haemoglobin [HbA1c (∆HbA1c)], incident diabetes, total all-cause hospitalizations (first + recurrent), and a composite of all-cause mortality and hospitalization for pneumonia or influenza via a post-hoc analysis of the DANFLU-1 trial.

Methods: DANFLU-1 was a pragmatic, open-label trial randomizing adults (65-79 years) 1:1 to QIV-HD or QIV-SD during the 2021/22 influenza season. Follow-up ended on May 31, 2022Cox proportional hazards regression was used to estimate rVE against incident diabetes and the composite endpoint, negative binomial regression to estimate rVE against all-cause hospitalizations, and ANCOVA when assessing rVE against ∆HbA1c.

Results: Of the 12 477 participants, 1162 (9.3%) had diabetes at baseline. QIV-HD, compared with QIV-SD, was associated with a reduction in the rate of all-cause hospitalizations irrespective of diabetes [overall: 647 vs. 742 events, incidence rate ratio (IRR): 0.87, 95% CI (0.76-0.99); diabetes: 93 vs. 118 events, IRR: 0.80, 95% CI (0.55-1.15); without diabetes: 554 vs. 624 events, IRR: 0.88, 95% CI (0.76-1.01), pinteraction = 0.62]. Among those with diabetes, QIV-HD was associated with a lower risk of the composite outcome [2 vs. 11 events, HR: 0.18, 95% CI (0.04-0.83)] but had no effect on ∆HbA1c; QIV-HD adjusted mean difference: ∆ + 0.2 mmol/mol, 95% CI (−0.9 to 1.2). QIV-HD did not affect the risk of incident diabetes [HR 1.18, 95% CI (0.94-1.47)].

Conclusions: In this post-hoc analysis, QIV-HD versus QIV-SD was associated with an increased rVE against the composite of all-cause death and hospitalization for pneumonia/influenza, and the all-cause hospitalization rate irrespective of diabetes status.

Funding: The trial was funded by Sanofi.

Background & aim: Viral respiratory vaccine preventable diseases cause significant morbidity and mortality, especially among those with underlying medical conditions. Identifying such conditions associated with severe disease informs effective vaccination policy. We aimed to conduct an updated evidence review of the medical risk conditions for severe COVID-19, influenza and RSV disease and propose updates to existing vaccination guidance.

Methods: A targeted literature search was conducted in PubMed, Medline and Embase for medical risk conditions (as listed in the Australian Immunisation Handbook) associated with severe outcomes (hospitalisations, intensive care admissions or mortality) from COVID-19, influenza and RSV. The search included English full-text articles from the Omicron period (2021–present) for COVID-19 and from 1946–present for influenza and RSV.

Results: Across all three diseases, immunocompromising conditions, cardiac disease, chronic respiratory conditions, chronic neurological conditions and chronic kidney disease had the highest relative risks of severe disease. Depending on age and disease definition, risk ratios varied within and between some conditions, such as immunocompromise (aRR 5.8 for COVID-19, OR 13.6 for influenza, OR 2.0 for RSV), asthma (aRR 1.36 for COVID-19, OR 2.4 for influenza, OR 10.9 for RSV) and obesity (aRR 1.35 for COVID-19, OR 1.45 for influenza, OR 0.68 to 3.05 for RSV). Limited evidence was available for some conditions associated with severe COVID-19 or influenza, including non-diabetic chronic metabolic conditions, autoimmune hepatitis, non-alcoholic fatty liver disease and splenic dysfunction. There was no published evidence that identified chronic metabolic conditions, haematological disorders or chronic liver disease as risk factors for severe RSV disease.

Conclusion: Although there are some limitations, our review provides updated guidance on the medical risk conditions associated with severe COVID-19, influenza and RSV disease. Several key risk conditions were common across all three respiratory viruses, and some conditions, having limited evidence, were disease specific.

Background: Public health concerns due to ongoing emergence of SARS-CoV-2 variants necessitates further development of improved COVID-19 vaccines. One major innovation are self-amplifying mRNA vaccines such as ARCT-154 (Arcturus Therapeutics Inc.) which induces superior immunogenicity compared with conventional mRNA in terms of magnitude, breadth and persistence of neutralizing antibodies.

Methods: In a pivotal placebo-controlled trial in Vietnam combining phase 1, 2 and 3 cohorts, over 17,000 adults received at least one dose of ARCT-154. Here we report the safety and reactogenicity observations made (NCT05012943).

Results: ARCT-154 elicited more local reactions than saline placebo, mainly reports of mild/moderate and a few severe cases of injection site pain. Most frequent solicited adverse events were fatigue, myalgia, headache, arthralgia and chills. Solicited local and systemic reactogenicity resolved within 7 days. Long-term follow-up has not revealed any safety concerns, with no reports of myocarditis or pericarditis. Acceptable tolerability of ARCT-154 was also observed in older participants and in those liable to severe consequences of COVID-19 due to underlying medical conditions. No serious consequences occurred in several pregnancies reported after vaccination, with normal outcomes when followed to term.

Conclusions: Data from this large trial suggest that ARCT-154 is safe and well tolerated.

Background: The burden of pertussis or whooping cough in adults is underdiagnosed and underreported. This study aimed to determine the cumulative incidence of pertussis and vaccination coverage in adults in a primary care setting in Australia.

Methods: De-identified, aggregated data were extracted electronically from participating clinics using Medical Director (MD) primary care software for patients aged >=18 years, 2008-2019. MD is utilised by ~50% of General Practices in Australia. Eligible participants (active patients) were defined, and we estimated the cumulative incidence of diagnosed pertussis in adults by age group, at-risk populations, vaccine coverage and presence of pertussis complications in the study. We also examined the incidence of undiagnosed coughing illness in the study population.

Results: Diagnosis of pertussis was identified in 1,788 (0.2%) of all 764,864 active patients, with an average annual incidence of 76.9 per 100,000 population. The incidence rate varied by year and age group. The highest incidence was seen in 2011 (125.1 / 100,000). Western Australia had the highest incidence rate of pertussis, followed by New South Wales and Queensland. Pertussis incidence was slightly higher in adults aged 18-44 and 45-64 years, and among females (63.3%). Of cases with pertussis, 58.7% had comorbidities including asthma and COPD (24.9%), CVD (13.8%), diabetes (11.2%) and obesity (8.7%). 4.4% of cases had pertussis complications; the most common was pneumonia. Overall, Tdap vaccine coverage among cases was below 20%, and increased with age but was lower than the influenza vaccine coverage (53.4%). There were 31,110 (4.1%) adults with a coughing illness who were not diagnosed with pertussis during the years studied. The trends mostly followed that of pertussis.

Conclusion: In the primary care setting, a high burden of pertussis and low vaccination rates were seen in adults. The incidence of an unspecified coughing illness was also high in that setting, and a proportion of these may be undiagnosed pertussis.

We assessed the safety, performance, acceptability, and usability of the High-Density Microarray Patch (HD-MAP) for vaccination in adults aged 50 and over.

This study was a single-centre, open-label, single-arm intervention in healthy adults aged 50+. HDMAPs (vaccine-free) were applied by a trained user and self-administered. Participants received one excipient-coated HD-MAP to the volar forearm (FA) and the upper arm (UA) administered by a trained user. Participants then self-administered a HD-MAP to the FA and UA. Application sites were compared for skin response. Participants completed an online survey and participated in a semi-structured interview on acceptability and usability. Analyses were undertaken using descriptive statistics. Interviews were coded in NVivo12 and subject to thematic analysis. The study occurred from 8 September 2021 to 15 February 2022 in Brisbane, Australia.

Of 44 participants, 43 % (n = 19) were male, and 57 % (n = 25) female. The HD-MAP was well-tolerated, with no treatment-related serious adverse events. The increase in transepidermal water loss following self-administration was similar to that observed for trained user administration (UA: 7.5 fold vs 6-fold, FA: 6.1-fold vs 6.6 fold). Fluorescent dermatoscopy confirmed that HD-MAPs engaged with the skin surface and that self and trained user administrations were similar. All participants found the HD-MAP applicator easy to use. 82 % of participants preferred “vaccination” by HD-MAP should its efficacy be proven equivalent to intramuscular injection (IM). Participants reported high acceptance of the resulting transient marks on the skin (82 %). 98 % of participants agreed that self-administration of the HD-MAP at home, without supervision, was highly preferable for its convenience.

HD-MAPs were safe in adults 50+ years, and performance was effective, regardless of administrator. Participants preferred the HD-MAP for its ease of use and convenience in self-administration. This vaccine delivery method shows promise for future implementation for this population.

Background:
Paediatric liver transplant recipients are at high risk of vaccine-preventable infections due to immunosuppression and challenges completing vaccination schedules before transplantation. Queensland Liver Transplant Service (QLTS) partnered with Queensland Specialist Immunisation Service (QSIS) to improve immunisation outcomes through tailored vaccination plans. This study evaluated vaccination rates among paediatric liver transplant recipients comparing outcomes before and after collaboration. It also assessed eligibility for consideration of live vaccines.
Methods:
This single-centre retrospective observational study analysed immunisation status of paediatric liver transplant recipients managed by QLTS between January 2008 and January 2024. Vaccination status was evaluated using data from electronic medical records, pathology systems, and Australian Immunisation Register. National Immunisation Program (NIP) guidelines relevant to birth year were considered.
Results:
A total of 107 patients were analysed, with 48(45%) known to QSIS prior to transplant and 59(55%) not known. Patients seen by QSIS had significantly higher immunisation rates: At transplant, 98% of QSIS patients were up to date with routine vaccines (excluding live vaccines) compared to 73% of non-QSIS patients (p < 0.001). Including live vaccines, 67% of QSIS patients were up to date, compared to 44% of non-QSIS patients. Post-transplant, 93% of QSIS-engaged patients remained up to date with the (NIP) compared to 71%. Of 107 analysed patients, 5(4.7%) were fully eligible to receive live vaccines but had not yet received them, and 2(1.9%) had already been vaccinated post-transplant. A further 68(64%) were deemed potentially eligible, meeting clinical criteria but lacking serology results. QSIS patients also demonstrated improved uptake of medically at-risk (MAR) and Hepatitis A vaccines.
Conclusion:
This study underscores the significant impact of service collaboration in improving immunisation outcomes for paediatric liver transplant recipients. QSIS patients demonstrated markedly higher adherence to NIP and MAR schedules compared to non-QSIS patients, highlighting the value add of a specialised immunisation service.

TITLE
Post-MMR3 measles, mumps, and rubella antibody level changes in seronegative young adults.

ABSTRACT
Introduction
Waning vaccine-acquired immunity post 2-doses of measles, mumps, and rubella (MMR) vaccine is well documented, but commercial assays have limited sensitivity and specificity. We measured measles (Me), mumps (Mu) and rubella (Ru) antibody pre and post a third MMR (MMR3) using more sensitive assays.
Methods
Eligible participants were health science students seronegative by manufacturer thresholds (DiaSorin) to ≥1 of Me, Mu and Ru. In-house bead-based multiplex immunoassay (MIA) and Me neutralization (PRNT) assays were done at RIVM, Netherlands. The GMT and proportion reaching cut-offs were measured by MIA (Me: 0.12 IU/ml; Mu: 102.0 RIVM units (RU)/ml; rubella: 10 IU/ml).
Results
Of 725 students screened in 2021, 175 (24.1%) required MMR and 69 (39.4%) had pre- and post-MMR3 sera available [seronegativity by DiaSorin: Me: 34 (49.2%), Mu: 40 (57.9%); by MIA: Me: 5 (7.2%), Mu: 51 (73.9%), Ru: 13 (18.8%); by PRNT: Me: 7 (10.1%)]. Pre-MMR GMT (by MIA): Me: 0.4 IU/ml (95% CI 0.4, 0.6), Mu: 62.0 RU/ml (95% CI: 48.8, 78.8); Ru: 30.4 IU/ml (95% CI: 23.5, 39.4). Post-MMR GMT (by MIA; all seropositive except 2 (2.9%) for Mu): Me: 1.4 IU/ml (95% CI: 1.2, 1.6), Mu: 334.8 RU/ml (95% CI: 284.9, 393.5) and Ru: 104.7 IU/ml (95% CI: 89.9, 121.9). GMT ratio, post-MMR vs pre-MMR was significantly higher for lowest tertile of pre-MMR antibody, but absolute post-MMR GMT was highest in the highest pre-MMR tertile.
Conclusion
Post-MMR3, participants seronegative by any assay were measles seropositive on MIA and PRNT. Discrepancies between assays and the high prevalence of seronegativity for at least one of Me and Mu have implications for the value of serological screening versus universal MMR3 among young adult healthcare trainees in countries with long-standing elimination. More data needed on antibody persistence and its correlation with protection post-MMR3.