Vaccine-Preventable DiseasesNCT05499299
Volatility and Heterogeneity of Vaccine Sentiments Means Continuous Monitoring is Needed When Measuring Message Effectiveness
A study testing Google ads in people with Vaccine-Preventable Diseases and Vaccine Refusal, run by The University of Hong Kong at 1 site in Hong Kong.
Trial summary
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… Read more about this study
- Who is it for?
- Any ageHealthy volunteers can take part
- Conditions the study is for
- Vaccine-Preventable Diseases, Vaccine Refusal
- What is being tested?
- Google ads
- Type of treatment
- Vaccines, Lifestyle or therapy programme
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 127,000 participants
- Where
- 1 siteHong Kong
- Study dates
- 1 Jul 2021to 1 Apr 2022
- Phase
- Interventional
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages Any age
- All sexes
- Healthy volunteers accepted
- Child, Adult, Older adult
Who may be able to join
- General users of Google search in Hong Kong
Who cannot join
- None
Trial locations and contacts
1 site in 1 country.
About this study
Official title: 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.
Read the 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.
- Conditions
- Vaccine-Preventable Diseases, Vaccine Refusal
- Being tested
- Google ads
- Keywords
- Vaccine hesitancy, Google ads, Vaccine messages, Vaccine confidence
- Medical subject headings
- Vaccine-Preventable Diseases, Vaccination Refusal, Vaccination Hesitancy
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Google adsBehavioural
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
| Study group | Role | What they receive |
|---|---|---|
| Government | Active comparator | Participants were shown with the government slogan for the COVID-19 vaccine campaign in 2021. This was the control arm. Receives: Behavioral: Google ads |
| Comparison | Experimental | The ad emphasized that vaccine uptake in Hong Kong substantially lagged behind that in comparable populations such as Singapore and the UK. Receives: Behavioral: Google ads |
| Exemption | Experimental | The ad emphasized that vaccinated people could be exempted from some disruptive control measures such as mandatory testing Receives: Behavioral: Google ads |
| Family | Experimental | The ad prompted people to get vaccinated in order to protect their family. Receives: Behavioral: Google ads |
| Lottery | Experimental | The ad prompted people to get vaccinated in order to be eligible for the numerous COVID-19 lotteries in Hong Kong Receives: Behavioral: Google ads |
| Mortality | Experimental | The ad emphasized that COVID-19 has caused millions of deaths worldwide. Receives: Behavioral: Google ads |
| Reopen | Experimental | The ad prompted people to get vaccinated to help Hong Kong reopen sooner. Receives: Behavioral: Google ads |
What is being measured
The primary outcome is the main question the study is designed to answer.
Number of bookings following each message delivery within 6 hours
The number of bookings made within X = 6 hours following each message delivery
Measured: 6 hours
Secondary outcomes (2)
Number of bookings following each message delivery within 3 hours
The number of bookings made within X = 3 hours following each message delivery
Measured: 3 hours
Number of bookings following each message delivery within 12 hours
The number of bookings made within X = 12 hours following each message delivery
Measured: 12 hours
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted12 Aug 2022
- Study start1 Jul 2021
- Primary completion31 Oct 2021
- Study completion1 Apr 2022
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Vaccine-Preventable DiseasesStudies of the same condition, open and under way.
- More trials run by The University of Hong KongThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Health services research
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Single blind
- Who is masked
- Participant
- Enrolment
- 127,000 participants (actual)
Sponsor and investigators
- Lead sponsor
- The University of Hong Kong
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor
- Investigators
- Joseph T Wu, PhD, Principal investigator, The University of Hong Kong
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT05499299
- Sponsor's protocol ID
- UW21-428
- Status last verified
- Aug 2022
- First submitted
- 10 Aug 2022
- Last updated
- 16 Aug 2022
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Yes: Proposals should be directed to kathysleung@connect.hku.hk; to gain access, data requestors will need to sign a data access agreement
Study at a glance
From the registry record, last updated by the sponsor on 16 Aug 2022. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- The Effect of Optimised Online Advertising on the Uptake of COVID-19 Vaccines in Hong Kong
- ClinicalTrials.gov ID
- NCT05499299
- Acronym / sponsor ID
- UW21-428
- Conditions
- Vaccine-Preventable Diseases, Vaccine Refusal
- Keywords
- Vaccine hesitancy, Google ads, Vaccine messages, Vaccine confidence
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 127,000 participants (actual)
- Lead sponsor
- The University of Hong KongUniversity, hospital or other
- Study start
- 1 Jul 2021 (actual)
- Primary completion
- 31 Oct 2021 (actual)
- Study completion
- 1 Apr 2022 (actual)
- First posted
- 12 Aug 2022 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
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.
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 design
- Primary purpose
- Health services research
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Single blind (participant)
- Number of arms
- 7
| Arm | Type | Receives |
|---|---|---|
| Government | Active comparator | Behavioral: Google adsParticipants were shown with the government slogan for the COVID-19 vaccine campaign in 2021. This was the control arm. |
| Comparison | Experimental | Behavioral: Google adsThe ad emphasized that vaccine uptake in Hong Kong substantially lagged behind that in comparable populations such as Singapore and the UK. |
| Exemption | Experimental | Behavioral: Google adsThe ad emphasized that vaccinated people could be exempted from some disruptive control measures such as mandatory testing |
| Family | Experimental | Behavioral: Google adsThe ad prompted people to get vaccinated in order to protect their family. |
| Lottery | Experimental | Behavioral: Google adsThe ad prompted people to get vaccinated in order to be eligible for the numerous COVID-19 lotteries in Hong Kong |
| Mortality | Experimental | Behavioral: Google adsThe ad emphasized that COVID-19 has caused millions of deaths worldwide. |
| Reopen | Experimental | Behavioral: Google adsThe ad prompted people to get vaccinated to help Hong Kong reopen sooner. |
Who may qualify
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Child, Adult, Older adult
Key inclusion criteria (1 listed)
- General users of Google search in Hong Kong
Key exclusion criteria (1 listed)
- None
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Google adsIndividuals 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 | Behavioural | Comparison, Exemption, Family, Government, Lottery, Mortality, Reopen |
Primary outcome
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
2 secondary outcomes
Number of bookings following each message delivery within 3 hours
Time frame: 3 hours
Number of bookings following each message delivery within 12 hours
Time frame: 12 hours
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 16 Aug 2022.
- Individual participant dataSharing planned: Yes. Proposals should be directed to kathysleung@connect.hku.hk; to gain access, data requestors will need to sign a data access agreement
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Joseph T Wu, PhD principal investigator
The University of Hong Kong
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Google ads in people with Vaccine-Preventable Diseases and Vaccine Refusal, run by The University of Hong Kong at 1 site in Hong Kong.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 1 inclusion and 1 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 16 Aug 2022. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Hong Kong. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Number of bookings following each message delivery within 6 hours (time frame: 6 hours). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 16 Aug 2022; AzTrials last refreshed its copy on 8 Nov 2026.