Health Communication, Influenza, Vaccination Coverage
Conditions
Keywords
Influenza Vaccines, Elderly, Health Communication, Vaccination Coverage, Community-based Intervention, Vietnam
Brief summary
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.
Detailed description
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: * Intervention: O Mon Ward (urban) and Truong Thanh Commune (rural) * Control: Phuoc Thoi Ward (urban) and Truong Xuan Commune (rural) 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: * T0: Baseline survey, August 2025 (n=952) * T1: Follow-up survey, September 2026 (n=approximately 1,200) Participants at T0 and T1 are not necessarily the same individuals; the design captures population-level changes within randomised clusters. 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): * Two community health education sessions per intervention site for adults aged \>65 years and one cohabiting family member, with distribution of printed educational leaflets on influenza disease and vaccination. Attendance: O Mon Ward: Session 1 = 60 older adults + 40 family members, Session 2 = 57 older adults + 35 family members; Truong Thanh Commune: Session 1 = 60 + 38, Session 2 = 50 + 30. * One capacity-building workshop per site for healthcare workers and community health volunteers in vaccination counselling (O Mon Ward: n=30; Truong Thanh Commune: n=20). * Thirty household visits per site by trained community health volunteers to reinforce vaccination counselling. Phase 2 (September 2025 to September 2026, ongoing): * Health communication banners displayed at health stations and community information centres throughout the intervention period. * Healthcare worker vaccination counselling integrated into all routine clinical contacts at intervention site health stations. * Zalo-based digital communication: weekly educational content and personalised vaccination reminders (December 2025 to January 2026, coinciding with peak influenza season in southern Vietnam). 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.
Interventions
BEHAVIORALMulti-component Health Communication Package
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).
Sponsors
Can Tho University of Medicine and Pharmacy
National Institute of Hygiene and Epidemiology, Vietnam
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
PREVENTION
Masking
NONE
Masking description
Due to the nature of the community-based health communication intervention, masking of participants and investigators is not feasible.
Intervention model description
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.
Eligibility
Sex/Gender
ALL
Age
66 Years to No maximum
Healthy volunteers
Yes
Inclusion criteria
* Residents living in selected wards/communes in Can Tho City for at least 6 months. * Aged above 65 years. * Mentally and physically capable of participating in interviews and receiving communication interventions. * Agree to participate in the study and provide informed consent.
Exclusion criteria
* Individuals with severe cognitive impairment or dementia. * Individuals with contraindications to influenza vaccination. * Planning to move out of the study area during the 12-month follow-up period.
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Influenza vaccination uptake in the preceding 12 months | Up to 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. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Influenza vaccination in calendar year 2025 | Up to 12 months | Proportion vaccinated against influenza during calendar year 2025, assessed by self-report at follow-up (September 2026). |
| Influenza vaccination intention | Baseline and up to 12 months | Proportion intending to receive influenza vaccination in the next 12 months, assessed by self-report at baseline (August 2025) and follow-up (September 2026). |
| Healthcare worker vaccination counselling | Baseline and up to 12 months | 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). |
| Influenza knowledge score | Baseline and up to 12 months | 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. |
| Vaccine hesitancy score (WHO-SAGE Vaccine Hesitancy Scale) | Baseline and up to 12 months | 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. |
| Willingness to pay for influenza vaccination | Baseline and up to 12 months | 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). |
Countries
Vietnam
Outcome results
None listed