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| Name | Class |
|---|---|
| National Institute of Hygiene and Epidemiology, Vietnam | OTHER |
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This study evaluates the effectiveness of a multi-component community-based communication intervention to increase influenza vaccination rates among adults aged above 65 years in Can Tho City, Vietnam. Using a cluster randomised controlled trial design with stratified lottery randomisation, four study sites were selected from eight sites surveyed in a prior study: O Mon Ward and Truong Thanh Commune (intervention); Phuoc Thoi Ward and Truong Xuan Commune (control). The intervention includes community health education sessions, healthcare worker training, household visits, health communication banners, and Zalo-based vaccination reminders, delivered over 12 months (September 2025 to September 2026). Effectiveness is assessed by comparing pre- and post-intervention outcomes using Difference-in-Differences (DID) analysis.
This study employs a cluster randomised controlled trial (cluster RCT) design with a repeated cross-sectional approach. The unit of randomisation is the cluster (ward or commune).
RANDOMISATION:
From eight study sites surveyed in Objective 1 (four urban wards and four rural communes in Can Tho City), four sites were selected by stratified lottery randomisation. Within each stratum (urban and rural), one site was randomly assigned to the intervention group and one to the control group by lottery draw without investigator discretion:
PARTICIPANTS:
All eligible permanent residents aged above 65 years at each study site were invited to participate. Data are collected at two independent cross-sectional time points:
INTERVENTION (12 months: September 2025 to September 2026):
The 12-month duration encompasses both active implementation and the time required for knowledge, attitude, and behaviour change.
Phase 1 (September 2025, intensive activities):
Phase 2 (September 2025 to September 2026, ongoing):
CONTROL GROUP:
Received routine primary healthcare only, with no additional study-related activities.
ANALYSIS:
Effectiveness is measured using Difference-in-Differences (DID) regression, comparing changes between T0 and T1 across intervention and control clusters. Models use multivariable logistic regression (binary outcomes) and linear regression (continuous outcomes), adjusted for sociodemographic covariates. Intraclass correlation coefficients (ICC) were estimated for all outcomes and found to be negligible (ICC < 0.01), confirming the appropriateness of individual-level DID analysis.
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| Label | Type | Description | Intervention Names |
|---|---|---|---|
| Multi-component Health Communication | Experimental | Adults aged >65 years in 2 intervention clusters (O Mon Ward and Truong Thanh Commune) receive a multi-component package: Phase 1 (Sep 2025): (1) Two community health education sessions/ site for older adults and one family member, with influenza leaflets. (2) One HCW capacity-building workshop/site (O Mon: n=30; Truong Thanh: n=20). (3) Thirty household visits/site by community health volunteers. Phase 2 (Sep 2025-Sep 2026): (4) Health communication banners at health stations and community centres. (5) HCW point-of-care vaccination counselling at all clinical contacts. (6) Zalo-based weekly reminders and educational content (Dec 2025-Jan 2026). |
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| Routine Immunization Information | No Intervention | Participants in this arm receive standard care and routine immunization information provided by the local health station without the additional communication package. |
| Name | Type | Description | Arm Group Labels | Other Names |
|---|---|---|---|---|
| Multi-component Health Communication Package | Behavioral | A 12-month cluster-level communication intervention (Sep 2025-Sep 2026) delivered in two phases to all adults aged >65 years in intervention clusters: Phase 1 (Sep 2025): (1) Two community health education sessions/site with influenza leaflets for older adults and family members; (2) HCW capacity-building workshop/site (O Mon: n=30; Truong Thanh: n=20); (3) Thirty household visits/site by community health volunteers. Phase 2 (ongoing): (4) Health communication banners at health stations and community centres; (5) HCW point-of-care vaccination counselling at all clinical contacts; (6) Zalo-based weekly educational content and vaccination reminders (Dec 2025-Jan 2026). |
| Measure | Description | Time Frame |
|---|---|---|
| Influenza vaccination uptake in the preceding 12 months | Proportion of participants who received influenza vaccination in the 12 months prior to survey, assessed by self-report. Baseline assessed August 2025; follow-up assessed September 2026. Intervention effect estimated using Difference-in- Differences (DID) regression comparing change between intervention and control clusters. | Up to 12 months |
| Measure | Description | Time Frame |
|---|---|---|
| Influenza vaccination in calendar year 2025 | Proportion vaccinated against influenza during calendar year 2025, assessed by self-report at follow-up (September 2026). | Up to 12 months |
| Influenza vaccination intention |
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Inclusion Criteria:
Exclusion Criteria:
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| Facility | Status | City | State | ZIP | Country | Contacts |
|---|---|---|---|---|---|---|
| Can Tho University of Medicine and Pharmacy | Can Tho | Can Tho City | 900000 | Vietnam |
Individual participant data (IPD) will not be shared with other researchers to ensure the privacy and confidentiality of the study participants, in accordance with local ethical guidelines and institutional policies. Only aggregated results will be made available through publications.
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| ID | Term |
|---|---|
| D007251 | Influenza, Human |
| ID | Term |
|---|---|
| D012141 | Respiratory Tract Infections |
| D007239 | Infections |
| D009976 | Orthomyxoviridae Infections |
| D012327 | RNA Virus Infections |
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A cluster randomized controlled trial where wards/communes are the unit of randomization. Participants in intervention clusters receive multi-component communication, while control clusters receive standard care.
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Due to the nature of the community-based health communication intervention, masking of participants and investigators is not feasible.
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Proportion intending to receive influenza vaccination in the next 12 months, assessed by self-report at baseline (August 2025) and follow-up (September 2026).
| Baseline and up to 12 months |
| Healthcare worker vaccination counselling | Proportion who received influenza vaccination counselling from a healthcare worker or community health volunteer in the preceding 12 months, assessed by self-report at baseline (August 2025) and follow-up (September 2026). | Baseline and up to 12 months |
| Influenza knowledge score | Total knowledge score (0-6) on influenza disease aetiology, transmission, complications, and vaccine characteristics. Higher scores indicate greater knowledge. Assessed at baseline (August 2025) and follow-up (September 2026). Analysed using linear regression DID. | Baseline and up to 12 months |
| Vaccine hesitancy score (WHO-SAGE Vaccine Hesitancy Scale) | Vaccine hesitancy measured using the WHO-SAGE Vaccine Hesitancy Scale (Vietnamese-adapted version). Higher scores indicate greater hesitancy. Assessed at baseline (August 2025) and follow-up (September 2026). Analysed using linear regression DID. | Baseline and up to 12 months |
| Willingness to pay for influenza vaccination | Proportion willing to pay out-of-pocket costs for influenza vaccination, assessed by self-report binary question at baseline (August 2025) and follow-up (September 2026). | Baseline and up to 12 months |
| D014777 | Virus Diseases |
| D012140 | Respiratory Tract Diseases |