Volatility and Heterogeneity of Vaccine Sentiments Means Continuous Monitoring is Needed When Measuring Message Effectiveness

August 12, 2022 updated by: The University of Hong Kong

The Effect of Optimised Online Advertising on the Uptake of COVID-19 Vaccines in Hong Kong

The success of vaccination programs often depends on the effectiveness of the vaccine messages, particularly during emergencies such as the COVID-19 pandemic. The current suboptimal uptake of COVID-19 vaccines across many parts of the world highlights the tremendous challenges in overcoming vaccine hesitancy and refusal even in the context of a world-devastating pandemic. The investigators conducted a randomized controlled trial in Hong Kong to evaluate the impact of seven vaccine messages on COVID-19 vaccine uptake (with the government slogan as the control). The participants included 127,000 individuals who googled COVID-19-related information during July-October 2021.

Study Overview

Status

Completed

Conditions

Intervention / Treatment

Detailed Description

This study aims to evaluate the effectiveness of using the Google advertising platforms on influencing the uptake of COVID-19 vaccines in Hong Kong. When completed, the rich database compiled through this proposed study will provide increased insight into vaccine hesitancy in Hong Kong. Insights from the optimised online advertising trial can aid in providing crucial technical and theoretical support to the relevant health authorities for any potential evidence-based policy intervention in addressing vaccine hesitancy issues or the public's concerns towards vaccines in Hong Kong.

Study Type

Interventional

Enrollment (Actual)

127000

Phase

  • 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 Locations

  • Hong Kong
      • Hong Kong, Hong Kong
        • The University of Hong Kong

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

Ages Eligible for Study

  • ADULT
  • OLDER_ADULT
  • CHILD

Accepts Healthy Volunteers

Yes

Genders Eligible for Study

All

Description

Inclusion Criteria:

  • General users of Google search in Hong Kong

Exclusion Criteria:

  • None

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: HEALTH_SERVICES_RESEARCH
  • Allocation: RANDOMIZED
  • Interventional Model: PARALLEL
  • Masking: SINGLE

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
ACTIVE_COMPARATOR: Government
Participants were shown with the government slogan for the COVID-19 vaccine campaign in 2021. This was the control arm.
Behavioral: Google ads
Individuals who googled COVID-19 information in Hong Kong were randomized to see one of the seven ads and, if they clicked on the ads, the corresponding vaccine message on our website
EXPERIMENTAL: Comparison
The ad emphasized that vaccine uptake in Hong Kong substantially lagged behind that in comparable populations such as Singapore and the UK.
Behavioral: Google ads
Individuals who googled COVID-19 information in Hong Kong were randomized to see one of the seven ads and, if they clicked on the ads, the corresponding vaccine message on our website
EXPERIMENTAL: Exemption
The ad emphasized that vaccinated people could be exempted from some disruptive control measures such as mandatory testing
Behavioral: Google ads
Individuals who googled COVID-19 information in Hong Kong were randomized to see one of the seven ads and, if they clicked on the ads, the corresponding vaccine message on our website
EXPERIMENTAL: Family
The ad prompted people to get vaccinated in order to protect their family.
Behavioral: Google ads
Individuals who googled COVID-19 information in Hong Kong were randomized to see one of the seven ads and, if they clicked on the ads, the corresponding vaccine message on our website
EXPERIMENTAL: Lottery
The ad prompted people to get vaccinated in order to be eligible for the numerous COVID-19 lotteries in Hong Kong
Behavioral: Google ads
Individuals who googled COVID-19 information in Hong Kong were randomized to see one of the seven ads and, if they clicked on the ads, the corresponding vaccine message on our website
EXPERIMENTAL: Mortality
The ad emphasized that COVID-19 has caused millions of deaths worldwide.
Behavioral: Google ads
Individuals who googled COVID-19 information in Hong Kong were randomized to see one of the seven ads and, if they clicked on the ads, the corresponding vaccine message on our website
EXPERIMENTAL: Reopen
The ad prompted people to get vaccinated to help Hong Kong reopen sooner.
Behavioral: Google ads
Individuals who googled COVID-19 information in Hong Kong were randomized to see one of the seven ads and, if they clicked on the ads, the corresponding vaccine message on our website

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Number of bookings following each message delivery within 6 hours
Time Frame: 6 hours
The number of bookings made within X = 6 hours following each message delivery
6 hours

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Number of bookings following each message delivery within 3 hours
Time Frame: 3 hours
The number of bookings made within X = 3 hours following each message delivery
3 hours
Number of bookings following each message delivery within 12 hours
Time Frame: 12 hours
The number of bookings made within X = 12 hours following each message delivery
12 hours

Collaborators and Investigators

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

Sponsor

The University of Hong Kong

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)

July 1, 2021

Primary Completion (ACTUAL)

October 31, 2021

Study Completion (ACTUAL)

April 1, 2022

Study Registration Dates

First Submitted

August 10, 2022

First Submitted That Met QC Criteria

August 10, 2022

First Posted (ACTUAL)

August 12, 2022

Study Record Updates

Last Update Posted (ACTUAL)

August 16, 2022

Last Update Submitted That Met QC Criteria

August 12, 2022

Last Verified

August 1, 2022

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • UW21-428

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

YES

IPD Plan Description

Proposals should be directed to kathysleung@connect.hku.hk; to gain access, data requestors will need to sign a data access agreement

IPD Sharing Time Frame

Beginning 9 months and ending 36 months following article publication

IPD Sharing Access Criteria

Researchers who provide a methodologically sound proposal for meta-analysis. Proposals should be directed to Kathyleung@connect.hku.hk; to gain access, data requestors will need to sign a data access agreement.

IPD Sharing Supporting Information Type

  • STUDY_PROTOCOL

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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