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

• Sponsor: The University of Hong Kong (Other)
• Overall Status: Completed
• CT.gov ID: NCT05499299
• Collaborator: (none)
• Enrollment: 127,000
• Location: 1
• Arms: 7
• Actual Duration (Months): 9
• Patients Per Site Per Month: 14107.9

Study Details

Study Description

Brief 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 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.

Condition or Disease	Intervention/Treatment	Phase
Vaccine-Preventable Diseases; Vaccine Refusal	Behavioral: Google ads	N/A

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

• Study Type: Interventional
• Actual Enrollment: 127000 participants
• Allocation: Randomized
• Intervention Model: Parallel Assignment
• Masking: Single (Participant)
• Primary Purpose: Health Services Research
• Official Title: The Effect of Optimised Online Advertising on the Uptake of COVID-19 Vaccines in Hong Kong
• Actual Study Start Date: Jul 1, 2021
• Actual Primary Completion Date: Oct 31, 2021
• Actual Study Completion Date: Apr 1, 2022

Arms and Interventions

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

Outcome Measures

Primary Outcome Measures

1. Number of bookings following each message delivery within 6 hours [6 hours]

   The number of bookings made within X = 6 hours following each message delivery

Secondary Outcome Measures

1. Number of bookings following each message delivery within 3 hours [3 hours]

   The number of bookings made within X = 3 hours following each message delivery

2. Number of bookings following each message delivery within 12 hours [12 hours]

   The number of bookings made within X = 12 hours following each message delivery

Eligibility Criteria

Criteria

• Ages Eligible for Study: N/A and Older
• Sexes Eligible for Study: All
• Accepts Healthy Volunteers: Yes

Inclusion Criteria:

• General users of Google search in Hong Kong

Exclusion Criteria:

• None

Contacts and Locations

Locations

	Site	City	State	Country	Postal Code
1	The University of Hong Kong	Hong Kong		Hong Kong

Sponsors and Collaborators

• The University of Hong Kong

Investigators

• Principal Investigator: Joseph T Wu, PhD, The University of Hong Kong

Study Documents (Full-Text)

None provided.

More Information

Publications

None provided.

• Responsible Party: The University of Hong Kong
• ClinicalTrials.gov Identifier: NCT05499299
• Other Study ID Numbers: UW21-428
• First Posted: Aug 12, 2022
• Last Update Posted: Aug 16, 2022
• Last Verified: Aug 1, 2022

• Individual Participant Data (IPD) Sharing Statement: Yes
• Plan to Share IPD: Yes
• Studies a U.S. FDA-regulated Drug Product: No
• Studies a U.S. FDA-regulated Device Product: No
• Keywords provided by The University of Hong Kong: Vaccine hesitancy; Google ads; Vaccine messages; Vaccine confidence
• Additional relevant MeSH terms: Vaccine-Preventable Diseases

Study Results

No Results Posted as of Aug 16, 2022