Nudging towards COVID-19 and influenza vaccination uptake in medically at-risk children: EPIC study protocol of randomised controlled trials in Australian paediatric outpatient clinics.

INTRODUCTION: Children with chronic medical diseases are at an unacceptable risk of hospitalisation and death from influenza and SARS-CoV-2 infections. Over the past two decades, behavioural scientists have learnt how to design non-coercive 'nudge' interventions to encourage positive health behaviours. Our study aims to evaluate the impact of multicomponent nudge interventions on the uptake of COVID-19 and influenza vaccines in medically at-risk children. METHODS AND ANALYSES: Two separate randomised controlled trials (RCTs), each with 1038 children, will enrol a total of approximately 2076 children with chronic medical conditions who are attending tertiary hospitals in South Australia, Western Australia and Victoria. Participants will be randomly assigned (1:1) to the standard care or intervention group. The nudge intervention in each RCT will consist of three text message reminders with four behavioural nudges including (1) social norm messages, (2) different messengers through links to short educational videos from a paediatrician, medically at-risk child and parent and nurse, (3) a pledge to have their child or themselves vaccinated and (4) information salience through links to the current guidelines and vaccine safety information. The primary outcome is the proportion of medically at-risk children who receive at least one dose of vaccine within 3 months of randomisation. Logistic regression analysis will be performed to determine the effect of the intervention on the probability of vaccination uptake. ETHICS AND DISSEMINATION: The protocol and study documents have been reviewed and approved by the Women's and Children's Health Network Human Research Ethics Committee (HREC/22/WCHN/2022/00082). The results will be published via peer-reviewed journals and presented at scientific meetings and public forums. TRIAL REGISTRATION NUMBER: NCT05613751.

Interventions for increasing the uptake of immunisations in healthcare workers: A systematic review.

OBJECTIVE: This systemic review aimed to evaluate the effectiveness of interventions for increasing the uptake of immunisation in healthcare workers (HCWs) compared to no or alternative interventions. METHODS: A systematic review was undertaken (until March 2022) using a search strategy established a priori to capture studies that examined the effect of interventions on vaccination levels in HCWs. We included randomised controlled trials (RCT), cluster RCTs, controlled before-after (CBA) studies and interrupted time-series (ITS) studies. We described studies descriptively and synthesized results with a fixed-effect or random-effects model meta-analysis, where appropriate. The risk of bias was assessed for each study; the quality evidence per comparison was assessed using Grading of Recommendations Assessment, Development and Evaluation (GRADE). RESULTS: We identified three RCTs, six cluster RCTs and four ITS studies. There was a diverse range of interventions; many included an educational component. Based on the evidence examined the following may be effective strategies in increasing the proportion of HCWs vaccinated: policy interventions, targeted and multicomponent strategies, tailored programs directed at management, physician delivered education with a vaccine 'champion' and individual decision analysis. Limited eligible studies restricted synthesis and interpretation of findings. No studies evaluated the effectiveness of legislation. Nor did we find studies evaluating the effectiveness of incentives on their own or studies focusing solely on improving access to vaccination. We judged all the studies as either unclear or high risk of bias. CONCLUSION: Few robust studies that evaluate interventions to increase vaccination in HCWs are available. A limitation of this systematic review is that interventions are diverse, poorly reported and few were sufficiently alike to combine in an evaluation. More research on the effects of interventions to increase vaccination in HCWs is required, this should address a variety of vaccines and not just influenza vaccination.

Randomised controlled trials of behavioural nudges delivered through text messages to increase influenza and COVID-19 vaccines among pregnant women (the EPIC study): study protocol.

BACKGROUND: Influenza and COVID-19 infections during pregnancy may have serious adverse consequences for women as well as their infants. However, uptake of influenza and COVID-19 vaccines during pregnancy remains suboptimal. This study aims to assess the effectiveness of a multi-component nudge intervention to improve influenza and COVID-19 vaccine uptake among pregnant women. METHODS: Pregnant women who receive antenatal care at five tertiary hospitals in South Australia, Western Australia and Victoria will be recruited to two separate randomised controlled trials (RCTs). Women will be eligible for the COVID-19 RCT is they have received two or less doses of a COVID-19 vaccine. Women will be eligible for the influenza RCT if they have not received the 2023 seasonal influenza vaccine. Vaccination status at all stages of the trial will be confirmed by the Australian Immunisation Register (AIR). Participants will be randomised (1:1) to standard care or intervention group (n = 1038 for each RCT). The nudge intervention in each RCT will comprise three SMS text message reminders with links to short educational videos from obstetricians, pregnant women and midwives and vaccine safety information. The primary outcome is at least one dose of a COVID-19 or influenza vaccine during pregnancy, as applicable. Logistic regression will compare the proportion vaccinated between groups. The effect of treatment will be described using odds ratio with a 95% CI. DISCUSSION: Behavioural nudges that facilitate individual choices within a complex context have been successfully used in other disciplines to stir preferred behaviour towards better health choices. If our text-based nudges prove to be successful in improving influenza and COVID-19 vaccine uptake among pregnant women, they can easily be implemented at a national level. TRIAL REGISTRATION: ClinicalTrials.gov Identifier NCT05613751. Registered on November 14, 2022.

Barriers to COVID-19 vaccination of migrant populations: A qualitative interview study of immunisation providers in Victoria, Australia.

INTRODUCTION: This study aimed to understand barriers and enablers, future strategies, communication approaches and resources needed for COVID-19 vaccination among migrant communities in Melbourne, Australia. MATERIAL AND METHODS: We interviewed 24 immunisation providers who deliver immunisation services to migrant populations in Melbourne. We used the WHO Behavioural and Social Drivers framework (underlined) to organise barriers and enablers to COVID-19 vaccination. RESULTS: Participants believed migrants had concerns about vaccine safety and efficacy and saw vaccines as minimally beneficial in the 'low COVID-19' environment of Australia (what people think and feel). Healthcare providers with established relationships within migrant communities played key roles in vaccine advocacy (social processes). Migrants' vaccine motivation was mediated by health literacy, institutional trust and previous experiences with health services. Practical issues included perceived lack of information on vaccine booking process and accessibility challenges. CONCLUSIONS: Strategies to increase migrant vaccine coverage should utilise immunisation providers with community links and trusted local vaccine ambassadors to engage and address community vaccine concerns.

Short Message Service Reminder Nudge for Parents and Influenza Vaccination Uptake in Children and Adolescents With Special Risk Medical Conditions: The Flutext-4U Randomized Clinical Trial.

Importance: Children with chronic medical conditions are at increased risk of severe influenza. Uptake of influenza vaccination in children and adolescents with these identified special risk medical conditions (SRMCs) is suboptimal. Objective: To assess the effectiveness of Flutext-4U, a parent short message service (SMS) reminder nudge intervention, in increasing influenza immunization in children and adolescents with SRMCs. Design, Setting, and Participants: This randomized clinical trial was conducted at a tertiary pediatric hospital in Adelaide, South Australia, from April 15 to September 30, 2021. Children and adolescents aged 6 months to younger than 18 years with SRMCs and a subspecialist outpatient appointment over a 5-month period during the Australian seasonal influenza vaccination season (April-August 2021) were eligible to participate. Follow-up was until September 30, 2021. Interventions: Participants were randomly assigned (1:1 ratio) to control: clinician nudges (hospital vaccine availability, ease of access, and recommendation from hospital subspecialists) or SMS intervention (control conditions plus an additional SMS reminder nudge to parents), with randomization stratified by age group (<5 years, 5-14 years, or >14 to <18 years). Main Outcomes and Measures: The primary outcome was influenza vaccination, as confirmed by the Australian Immunisation Register. Results: A total of 600 participants (intervention group: 298 [49.7%]; mean [SD] age, 11.5 [4.6] years; 162 female participants [54.4%]; control group: 302 [50.3%]; mean [SD] age, 11.4 [4.7] years; 155 female participants [51.3%]) were included. Influenza vaccination was 38.6% (113 of 293) in the SMS intervention group compared with 26.2% (79 of 302) in the control group (adjusted odds ratio [aOR], 1.79; 95% CI, 1.27-2.55; P = .001). Time to vaccine receipt was significantly lower among SMS participants (adjusted hazard ratio, 1.67; 95% CI, 1.25-2.22; P < .001). For participants randomly assigned by June 15, a significantly greater proportion receiving the SMS intervention were vaccinated during the optimal delivery period April to June 30 (SMS group: 40.0% [76 of 190] vs 25.4% [50 of 197]; aOR, 1.97; 95% CI, 1.28-3.06; P = .002). Conclusions and Relevance: Results of this randomized clinical trial suggest that an additional SMS reminder nudge for parents delivered in the tertiary care hospital setting to children and adolescents with SMRCs resulted in higher influenza vaccine uptake compared with clinician nudges alone. Trial Registration: ANZCTR Identifier: ACTRN12621000463875.

Factors impacting COVID-19 vaccine decision making in older adults and people with underlying conditions in Victoria, Australia: A cross-sectional survey.

Australia's COVID-19 vaccine rollout included prioritizing older adults and those with underlying conditions. However, little was known around the factors impacting their decision to accept the vaccine. This study aimed to assess vaccine intentions, information needs, and preferences of people prioritized to receive the COVID-19 vaccine at the start of the Australian vaccine rollout. A cross-sectional online survey of people aged ≥70 years or 18-69 with chronic or underlying conditions was conducted between 12 February and 26 March 2021 in Victoria, Australia. The World Health Organization Behavioural and Social Drivers of COVID-19 vaccination framework and items informed the survey design and framing of results. Bivariate logistic regression was used to investigate the association between intention to accept a COVID-19 vaccine and demographic characteristics. In total, 1828 eligible people completed the survey. Intention to vaccinate was highest among those ≥70 years (89.6%, n = 824/920) versus those aged 18-69 years (83.8%, n = 761/908), with 91% (n = 1641/1803) of respondents agreeing that getting a COVID-19 vaccine was important to their health. Reported vaccine safety (aOR 1.4, 95% CI 1.1 to 1.8) and efficacy (aOR 1.9, 95% CI 1.5 to 2.3) were associated with intention to accept a COVID-19 vaccine. Concerns around serious illness, long-term effects, and insufficient vaccine testing were factors for not accepting a COVID-19 vaccine. Preferred communication methods included discussion with healthcare providers, with primary care providers identified as the most trusted information source. This study identified factors influencing the prioritized public's COVID-19 vaccine decision-making, including information preferences. These details can support future vaccination rollouts.

Catch-up immunisation for migrant children in Melbourne: A qualitative study with providers to determine key challenges.

BACKGROUND: Current models of immunisation service delivery in Australia are not meeting the needs of migrant children, who experience a higher burden of vaccine preventable disease and lower immunisation rates compared to non-migrant children. Understanding the experiences of immunisation providers is critical for designing effective and tailored interventions to improve this service. This study aimed to identify the facilitators and barriers to providers delivering a comprehensive catch-up immunisation service to migrant children in Melbourne, Australia. METHODS: Semi-structured interviews with council and general practice immunisation providers were conducted. Recorded interviews were transcribed and coded inductively using thematic analysis. Identified themes were then deductively categorised according to the Capability, Opportunity and Motivation of Behaviour (COM-B) model. RESULTS: Twenty-four providers (five practice nurses, six general practitioners, six council nurses and seven council administration officers) were interviewed between March and June 2021. Fourteen themes were identified that contributed to the delivery of an effective catch-up immunisation service. Capability themes included training, experience and skills to perform the service and communicate with families. Opportunity themes incorporated time, workplace norms, traits of migrant families, costs, systems and resources. Themes related to motivation were provider responsibility, beliefs about migrant health, and immunisation prioritisation. CONCLUSIONS: Key barriers for providers to deliver a comprehensive catch-up immunisation service were related to opportunity. Developing an online tool to support catch-up schedule development and reporting, and funding provider time to calculate the schedule are primary actions that could overcome opportunity barriers. Capability and motivation barriers for general practitioners included limited time, skills, and motivation compared to nurses. These barriers may be overcome with improvements to training that focus on upskilling nurses to deliver the catch-up service. Service delivery challenges are multifactorial, requiring a range of strategies to optimise this service and increase immunisation coverage in migrant children.

Respiratory syncytial virus, recurrent wheeze and asthma: A narrative review of pathophysiology, prevention and future directions.

Globally, respiratory syncytial virus (RSV) is the leading cause of bronchiolitis and pneumonia in young children, and the association between severe RSV disease and later recurrent wheeze and asthma is well established. Whilst a causal link between RSV and wheeze/asthma is not yet proven, immunological evidence suggests skewing towards a Th2-type response, and dampening of IFN-γ antiviral immunity during RSV infection underpins airway hyper-reactivity in a subset of susceptible children after RSV infection. Age at primary RSV infection, viral co-infection and genetic influences may act as effect-modifiers. Despite the significant morbidity and mortality burden of RSV disease in children, there is currently no licensed vaccine. Recent advancements in RSV preventatives, including long-acting monoclonal antibodies and maternal vaccinations, show significant promise and we are on the cusp of a new era in RSV prevention. However, the potential impact of RSV preventatives on subsequent wheeze and asthma remains unclear. The ongoing COVID-19 pandemic and associated public health measures have disrupted the usual seasonality of RSV. Whilst this has posed challenges for health-care services it has also enhanced our understanding of RSV transmission. The near absence of RSV cases during the first year of the pandemic in the context of strict public health measures has provided a rare opportunity to study the impact of delayed age of primary RSV infection on asthma prevalence. In this review, we summarise current understanding of the association between RSV, recurrent wheeze and asthma with a focus on pathophysiology, preventative strategies and future research priorities.

Examining the discourse regarding the delivery of occupational infection prevention and control training to healthcare workers: a scoping review of pandemic plans of 23 countries.

BACKGROUND: Over the years, countries reformed their pandemic plans but still healthcare systems were unprepared to handle the COVID-19 pandemic. Throughout the COVID-19 pandemic, healthcare workers (HCWs) raised issues around shortage of personal protective equipment (PPE), inadequate occupational infection prevention and control (IPC) training, lack of guidance regarding reuse/extended use of PPE and absence of HCWs. OBJECTIVE: The objective of this scoping review was to compare national and transnational pandemic plans and COVID-19 guidelines for the inclusion of recommendations regarding pandemic-specific occupational IPC training for HCWs, as well as strategies for managing the surge in PPE needs and staffing. INCLUSION CRITERIA: From each of the six WHO defined world regions, four countries with the highest burden of COVID-19 cases (as of mid-2020) were selected and attempted to locate the relevant pandemic plans and COVID-19 guidelines. METHODS: Searches were undertaken of 1: National Guidelines Clearinghouse, 2: websites of international public healthcare agencies such as WHO, the European Centre for Disease Prevention and Control (ECDC) and, 3: in-country health departments/Ministry of Health/Department of Public Health, between June 2020 and July 2021. The data were summarised under six themes drawn from publicly available pandemic plans and COVID-19 (IPC) guidelines of WHO, ECDC and 23 countries. RESULTS: The WHO, ECDC and 14 countries reported pandemic-specific IPC training; however, only four discussed training HCWs on correct PPE use; six countries listed strategies to manage the surge in demand of HCWs, while only five discussed managing the shortage of PPE. None of the COVID-19 guidelines recommended training HCWs for correct reuse or extended use of PPE and only one country's guideline outlined mandatory HCWs attendance and delivery of training in a regional language. CONCLUSION: Pandemic plans should be revised to include guiding principles regarding the delivery of pandemic specific IPC training. There is also a need to provide guidance on when countries should consider reuse and extended use of PPE. This discourse should also be reflected in disease-specific pandemic guidelines, like COVID-19 (IPC) guidelines. The aim of this review is to assist international health agencies in generating evidence-based guideline updates.

P3-MumBubVax intervention adaptation for general practitioners: A qualitative interview study.

BACKGROUND AND OBJECTIVES: General practitioners (GPs) are often the first source of vaccine information for expectant parents. A multicomponent intervention package (P3-MumBubVax) has been designed for midwives, but interventions to support GPs' vaccine discussions are limited. This qualitative study explored Australian GPs' attitudes, practices and educational needs to inform adaptation of the P3-MumBubVax intervention for primary care. METHOD: Semi-structured interviews with 30 GPs explored attitudes towards recommending maternal vaccines, vaccine communication approaches and training preferences. Data were analysed using thematic template analysis. RESULTS: Vaccination was central to the role of GPs and most felt confident discussing vaccines. GPs had opportunities to discuss maternal vaccines before and during pregnancy using a variety of communication techniques. GPs preferred convenient, interactive training with examples and up-to-date maternal vaccine resources. DISCUSSION: Findings informed adaptation of the P3-MumBubVax intervention, which offers GPs tailored vaccine resources, online communication training and interactive quizzes for individual or group learning.

Using provider-parent strategies to improve influenza vaccination in children and adolescents with special risk medical conditions: a randomised controlled trial protocol.

INTRODUCTION: Influenza immunisation is a highly cost-effective public health intervention. Despite a comprehensive National Immunisation Program, influenza vaccination in children and adolescents with special risk medical conditions (SRMCs) is suboptimal. Flutext-4U is an innovative, multi-component strategy targeting paediatric hospitals, general practice and parents of children and adolescents with SRMC. The Flutext-4U study aims to assess the impact of Flutext-4U to increase influenza immunisation in children and adolescents with SRMC. METHODS AND ANALYSIS: This is a randomised controlled trial involving parents of children and adolescents (aged >6 months to <18 years) with SRMC receiving tertiary care at the Women's and Children's Hospital (WCH), Adelaide, South Australia, who are eligible for funded influenza immunisation with a hospital appointment between the start of the seasonal influenza vaccination season and 31 July 2021, their treating general practitioners (GPs), and WCH paediatric specialists.Parents (of children/adolescents with SRMC) are randomised (1:1 ratio) to standard care plus intervention (SMS reminder messages to parents; reminders (written correspondence) for their child's GP from the hospital's Paediatric Outpatients Department) or standard care (hospital vaccine availability, ease of access and reminders for WCH subspecialists) with randomisation stratified by age-group (<5, 5-14, >14 to <18 years).The primary outcome is influenza vaccination, as confirmed by the Australian Immunisation Register.The proportion vaccinated (primary outcome) will be compared between randomised groups using logistic regression, with adjustment made for age group at randomisation. The effect of treatment will be described using an OR with a 95% CI. ETHICS AND DISSEMINATION: The protocol and all study materials have been reviewed and approved by the Women's and Children's Health Network Human Research Ethics Committee (HREC/20/WCHN/5). Results will be disseminated via peer-reviewed publication and at scientific meetings, professional and public forums. TRIAL REGISTRATION NUMBER: Australian New Zealand Clinical Trials Registry (ACTRN12621000463875).

The 2018 annual cost burden for children under five years of age hospitalised with respiratory syncytial virus in Australia.

ABSTRACT: Respiratory syncytial virus (RSV) is one of the principal causes of acute bronchiolitis and respiratory tract infections in young children. Routine RSV surveillance in Australian children is limited; vaccines are in late stage development; prophylactic monoclonal antibody (mAb) treatment is available but expensive; and there has been uncertainty around the cost burden. The objective of this study was to determine the annual cost burden for children under five years of age hospitalised with RSV in a single health service in 2018, with national extrapolation based on published Australian prevalence data. The methods utilised individual patient-level cost data prospectively collected for hospitalised children under five years of age in a tertiary Melbourne paediatric hospital. Results were extrapolated to all Australian children under five years of age to determine the national annual health cost burden, from a healthcare sector perspective over a 12 month time horizon. The results included 363 children with a mean age of 9.2 months (standard deviation, SD: 8.5 months). The mean cost per child was $17,120 (SD: $37,562), with a combined health service cost of $6,214,439. The reported Australian hospitalisation rate for RSV in the target age group ranged from 2.2 to 4.5 per 1,000 children under five years of age, resulting in a 2018 extrapolated cost range of $59,218,844-$121,129,453 for the estimated 3,459-7,075 children affected (combined index and all-cause six-month readmissions). This study concluded that RSV represents a significant cost burden to Australia's health care system. These data are important for future health economic assessments of preventative therapies, such as new RSV mAb treatments and maternal/childhood RSV vaccines, and provides valuable insights to inform health care planning and health policy.

Qualitative exploration of intentions, concerns and information needs of vaccine-hesitant adults initially prioritised to receive COVID-19 vaccines in Australia.

OBJECTIVE: Tailored communication is necessary to address COVID-19 vaccine hesitancy and increase uptake. We aimed to understand the information needs, perceived benefits and barriers to COVID-19 vaccination of people prioritised, but hesitant to receive the vaccine. METHOD: In this qualitative study in Victoria, Australia (February-May 2021), we purposively sampled hesitant adults who were health or aged/disability care workers (n=20), or adults aged 18-69 with comorbidities or aged ≥70 years ('prioritised adults'; n=19). We thematically analysed interviews inductively, then deductively organised themes within the World Health Organization Behavioural and Social Drivers of vaccination model. Two stakeholder workshops (n=12) explored understanding and preferences for communicating risks and benefits. We subsequently formed communication recommendations. RESULTS: Prioritised adults and health and aged care workers had short- and long-term safety concerns specific to personal circumstances, and felt like "guinea pigs". They saw vaccination as beneficial for individual and community protection and travel. Some health and aged care workers felt insufficiently informed to recommend vaccines, or viewed this as outside their scope of practice. Workshop participants requested interactive materials and transparency from spokespeople about uncertainty. Conclusions and public health implications: Eleven recommendations address communication content, delivery and context to increase uptake and acceptance of COVID-19 vaccines.

Parent-level barriers to uptake of childhood vaccination: a global overview of systematic reviews.

INTRODUCTION: Understanding barriers to childhood vaccination is crucial to inform effective interventions for maximising uptake. Published systematic reviews include different primary studies, producing varying lists of barriers. To make sense of this diverse body of literature, a comprehensive level of summary and synthesis is necessary. This overview of systematic reviews maps all potential parent-level barriers to childhood vaccination identified in systematic reviews. It synthesises these into a conceptual framework to inform development of a vaccine barriers assessment tool. METHODS: We applied Joanna Briggs methodology, searching the Epistemonikos review database and reference lists of included reviews to June 2020. Systematic reviews of qualitative or quantitative data on parent-level barriers to routine vaccination in preschool-aged children were included. Reviews addressing influenza, reporting non-modifiable determinants or reporting barriers not relevant to parents were excluded. Where possible, we extracted review details, barrier descriptions and the number, setting and design of primary studies. Two authors independently screened search results and inductively coded barrier descriptions. RESULTS: We screened 464 papers, identifying 30 relevant reviews with minimal overlap. Fourteen reviews included qualitative and quantitative primary studies, seven included quantitative and seven included qualitative studies only. Two did not report included study designs. Two-thirds of reviews (n=20; 67%) only included primary studies from high-income countries. We extracted 573 barrier descriptions and inductively coded these into 64 unique barriers in six overarching categories: (1) Access, (2) Clinic or Health System Barriers, (3) Concerns and Beliefs, (4) Health Perceptions and Experiences, (5) Knowledge and Information and (6) Social or Family Influence. CONCLUSIONS: A global overview of systematic reviews of parent-level barriers to childhood vaccine uptake identified 64 barriers to inform development of a new comprehensive survey instrument. This instrument will assess both access and acceptance barriers to more accurately diagnose the reasons for under-vaccination in children in different settings.

Comparing inductive and deductive analysis techniques to understand health service implementation problems: a case study of childhood vaccination barriers.

BACKGROUND: Effective implementation requires a comprehensive understanding of individual, organisational and system determinants. This study aimed to compare inductive and deductive analysis techniques to understand a complex implementation issue. We used childhood vaccination as a case study, an issue with wide-ranging barriers contributing to low-vaccine uptake internationally. METHODS: The study is based on the Behaviour Change Wheel framework, which was derived from several levels of theory: the 3 components of the COM-B framework (capability, opportunity and motivation) can be mapped to the 14 domains of the Theoretical Domains Framework (TDF), which is based on 84 underlying constructs. We first conducted a review of systematic reviews of parent-level barriers to childhood vaccination. Subsequently we (1) inductively coded these barriers into a data-driven framework, using thematic analysis, and (2) deductively mapped the barriers to COM-B and TDF domains and constructs. These processes were undertaken by two authors independently, and discrepancies were resolved through discussion. Inductive and deductive results were compared. RESULTS: The inductive process coded 583 descriptions of barriers identified from the literature into a framework of 74 barriers in 7 categories. The initial definitions used to map the barriers to deductive domains/constructs led to 89% agreement at the domain level. Resolving discrepancies required further definitions at the construct level. Of the 14 TDF domains, 10 were clearly identified in the data from the barrier reviews. Some domains were not specific enough to differentiate between types of barriers (e.g. Environmental Context and Resources), while other domains were not represented in the review data (e.g. Behavioural Regulation). CONCLUSIONS: Using both inductive and deductive analysis techniques can help achieve a more comprehensive understanding of barriers to health service implementation. The inductive categories represented the review data in a clearer way than the theoretical domains, with better differentiation; but the missing deductive domains were useful as a way to identify additional issues to investigate further. Both analysis techniques resulted in a comprehensive list of barriers to vaccination that would not have been achieved using either approach alone. We recommend a hybrid approach combining TDF with broader frameworks, for future researchers conducting evidence syntheses.