The study aims to retrospectively describe the demographic characteristics, comorbidity profiles, vaccination history and vaccination patterns of all individuals who have received at least one dose of TAK-003 (Qdenga) dengue vaccine at all VNVC centers between September 26, 2024 and September 30, 2025. The study will utilize existing data from the VNVC immunization database. No new data collection or direct participant contact will occur.
This is a retrospective, observational, multicenter study using existing vaccination records from the Vietnam Vaccine Joint Stock Company (VNVC) immunization database. The study will analyze data from all individuals who received at least one dose of the TAK-003 (Qdenga) dengue vaccine between September 26, 2024 and September 30, 2025. No new data collection or participant contact will be performed. The study will be conducted using data collected from all VNVC vaccination centers nationwide. VNVC is the most extensive private vaccination provider in Vietnam, with nearly 250 centers distributed across more than 50 provinces and cities. VNVC customers can be considered broadly representative of the Vietnamese population, reflecting a wide range of demographic, ethnic, and socioeconomic groups and levels. Data will be obtained from the VNVC centralized immunization database (Web-based), which systematically records all vaccination activities across VNVC centers nationwide. The database includes detailed demographic, clinical, and vaccination-related information collected during each client's visit. The VNVC data management team will extract relevant data fields for individuals who received at least one dose of TAK-003 during the study period. All data will be deidentified by VNVC before being shared with the research team in Tam Anh Research Institute (TAMRI). Personally identifiable information (e.g., name, phone numbers, address, or ID numbers) will be removed before transfer. The de-identified dataset will then be securely transferred to TAMRI. TAMRI's data management team will be responsible for data cleaning (identifying missing, inconsistent or duplicate entries), basic data validation and preparing dataset for statistical analysis. The finalized dataset will then be analyzed using standard statistical software. All analyses will be descriptive in nature, designed to characterize the demographic and clinical profile of individuals who received the TAK-003 vaccine and to estimate vaccination coverage and uptake patterns within the VNVC network. No inferential hypothesis testing will be performed.
Study Type
OBSERVATIONAL
Enrollment
800,000
Vietnam Vaccine Joint Stock Company
Ho Chi Minh City, Ho Chi Minh, Vietnam
Vaccination Coverage - First Dose
Percentage of the population that received the first dose of the TAK-003 vaccine
Time frame: Day 0 after recruitment
Vaccination Coverage - Second Dose
Percentage of the population that completed the two-dose TAK-003 series
Time frame: Day 0 after recruitment
To assess the coverage of TAK003 vaccine and its distribution across different strata, including sex, age brackets, geographic areas.
Descriptive analysis of primary outcomes, stratified by age group, sex, and geographic region where appropriate: * Age group Age of individuals at the first dose of the TAK-003 dengue vaccine administered, categorized by age groups. * Sex Distribution of male and female participants among those who received at least one dose of the TAK-003 vaccine. * Ethnicity Self-reported ethnic background of the vaccinated individuals. * Participant Occupation The employment status or professional category of the individuals at the time of vaccination. * Geographic Distribution - Participant Residence The province-level location of the participant's residence at the time of vaccination. * Geographic Distribution - Vaccination Site The specific VNVC vaccination center location where the TAK-003 vaccine was administered.
Time frame: Day 0 after recruitment
To assess the coverage of TAK003 vaccine and its distribution across different strata, including comorbidities
* Clinical Characteristics: Underlying Medical Conditions Presence or absence of pre-existing medical conditions at the time of vaccination. * Prevalence of Allergic History by Allergen Type: Number of participants with a history of allergy by allergen category. Categorization of participants based on their reported allergies to medications, food (e.g. seafood), previous vaccines, or other environmental allergens (e.g. weather). Unit of Measure: Number of participants
Time frame: Day 0 after recruitment
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