Assessment of Communication Interventions on Vaccination Knowledge and Acceptance (Y4F WP5/3)

November 2, 2026 updated by: Odette Wegwarth, Charite University, Berlin, Germany

Effectiveness Assessment of Communication Interventions to Improve Vaccination Knowledge and Acceptance

An online randomized controlled trial (RCT) examining the effectiveness of communication measures regarding TBE vaccination in the European context and yellow fever vaccination in the South American context on an informed vaccination decision. Building on an exploratory qualitative focus group study conducted in 2024 with vaccine-hesitant individuals (Ethics Committee Approval Number EA1/119/24) and an exploratory quantitative study conducted in 2025 among the general population in Germany and Colombia (Ethics Committee Approval Number EA2/112/25), the communication measures were designed to improve education about vaccinations and to increase individual willingness to be vaccinated.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Recruiting

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Detailed Description

The study design consists of an online survey. The questionnaire and the communication measures were developed in collaboration with the following partners: the Amsterdam Institute for Global Health and Development (AIGHD) in Amsterdam, the Netherlands, and CIDEIM (Centro Internacional de Entrenamiento e Investigaciones Médicas) in Cali, Colombia, based on the findings of the previous focus group studies and the subsequent quantitative study on the prevalence of knowledge about and acceptance of novel (flavivirus) vaccines and perceived barriers to vaccination among the general population in Germany and Colombia.

Potential participants will be invited to participate in the study by the panel provider Toluna via a link in an email. Individuals who express their willingness to participate will first be asked questions about their sociodemographic background, their vaccination status against TBE (Germany) or yellow fever (Colombia), as well as their perception of risk regarding TBE or yellow fever and the associated vaccinations.

Participants will then be randomly assigned in a 1:1:1 ratio to one of three study arms:

  • Control group (in Germany, a vaccination check based on the COVID-19 vaccination check on infektionsschutz.de; in Colombia, an educational video about the yellow fever vaccination from the Colombian Ministry of Health)
  • Intervention group 1: Information format A (website)
  • Intervention group 2: Information format B (slideshow/carousel)

In both countries, the intervention formats are implemented in the same way; only the vaccination being addressed differs (TBE in Germany, yellow fever in Colombia).

Within the two intervention groups, A and B, there is also a second randomized assignment to a presentation of an established (inactivated vaccine or live vaccine) versus a novel vaccine technology ("NovaCarrier"). This second randomization ensures that the assignment to vaccine technologies within the respective formats is not systematically linked to other participant characteristics. It serves exclusively to explore possible effects of the vaccine technologies on attitudes and intentions and does not form the basis of the primary case number planning.

Participants who view the materials featuring the hypothetical novel vaccine technology are transparently informed at the end of the study that this is a hypothetical technology.

Following the intervention, all participants will complete an adapted Informed Choice questionnaire (Marteau et al., 2001), which assesses risk understanding, knowledge, attitudes, and intention to be vaccinated against TBE or yellow fever. Subsequently, risk perception is assessed again after viewing an informational piece, and finally, participantsare asked two open-ended questions about safety and information needs regarding vaccinations.

The drafted communication measures will first be tested in a pilot study (n = 150; 75 participants per country) in order to adjust the materials to be developed before the main study (n = 1,374; 687 participants per country) if necessary. For this pilot study, the same questionnaire as for the main study will be used, with the addition of three open-ended questions regarding the information formats. The pilot study is not intended for final hypothesis testing, but solely to optimize the informational materials to be tested and, if necessary, the survey questions.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Estimated)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
1524

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

Study Contact Backup

Study Locations

  • Germany
    • State of Berlin
      • Berlin, State of Berlin, Germany, 10117
        • Recruiting
        • Charité - Universitätsmedizin Berlin, Berlin-Mitte

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

18 years and older (Adult, Older Adult)

Accepts Healthy Volunteers

Yes

Genders Eligible for Study

All

Description

Inclusion Criteria:

  • German citizens
  • Colombian citizens

Exclusion Criteria:

  • Citizens of all other countries

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Other
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Single

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Active Comparator: Intervention group 1 (website)

Participants are shown informational material A (website) before completing an adapted informed choice questionnaire that assesses participant risk understanding, knowledge, attitudes, and intention to get vaccinated against TBE/yellow fever.
Behavioral: Intervention group 1

Participants are shown informational material A (website)
Active Comparator: Intervention group 2 (slideshow/carousel)

Participants are shown informational material B (slideshow/carousel) before completing an adapted informed choice questionnaire that assesses participant risk understanding, knowledge, attitudes, and intention to get vaccinated against TBE/yellow fever.
Behavioral: Intervention group 2

Participants are shown informational material B (slideshow/carousel)
Placebo Comparator: Control group (vaccine check)

Participants are shown the control informational material (vaccine check) before completing an adapted informed choice questionnaire that assesses participant risk understanding, knowledge, attitudes, and intention to get vaccinated against TBE/yellow fever.
Other: Control format (vaccine check)

Participants are shown the control informational material (vaccine check)

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Relative frequency of informed decisions based on respective informational material
Time Frame: Immediately post intervention

The relative frequency of informed decisions based on the respective materials developed. Participants are classified into "informed" and "uninformed" based on their responses and the instrument developed my Marteau et al. (2001)
Immediately post intervention

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Charite University, Berlin, Germany

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
October 23, 2026

Primary Completion (Estimated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
November 1, 2026

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
November 1, 2026

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
November 2, 2026

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
November 2, 2026

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
November 6, 2026

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
November 6, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
November 2, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
November 1, 2026

More Information

Terms related to this study

Keywords

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • 2026_Y4F_WP5.3

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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