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

The University of Hong Kong (HKU)

Status: Completed

Conditions: Vaccine Refusal; Vaccine-Preventable Diseases

Treatments: Behavioral: Google ads

Study type: Interventional

Funder types: Other

Identifiers

NCT05499299

UW21-428

Details and patient eligibility

About

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.

Full 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.

Enrollment: 127,000 patients

Sex: All

Volunteers: Accepts Healthy Volunteers

Inclusion criteria

• General users of Google search in Hong Kong

Exclusion criteria

• None

Trial design

Primary purpose: Health Services Research

Allocation: Randomized

Interventional model: Parallel Assignment

Masking: Single Blind

---

127,000 participants in 7 patient groups

Government

Active Comparator group

Description:

Participants were shown with the government slogan for the COVID-19 vaccine campaign in 2021. This was the control arm.

Treatment:

Behavioral: Google ads

Comparison

Experimental group

Description:

The ad emphasized that vaccine uptake in Hong Kong substantially lagged behind that in comparable populations such as Singapore and the UK.

Treatment:

Behavioral: Google ads

Exemption

Experimental group

Description:

The ad emphasized that vaccinated people could be exempted from some disruptive control measures such as mandatory testing

Treatment:

Behavioral: Google ads

Family

Experimental group

Description:

The ad prompted people to get vaccinated in order to protect their family.

Treatment:

Behavioral: Google ads

Lottery

Experimental group

Description:

The ad prompted people to get vaccinated in order to be eligible for the numerous COVID-19 lotteries in Hong Kong

Treatment:

Behavioral: Google ads

Mortality

Experimental group

Description:

The ad emphasized that COVID-19 has caused millions of deaths worldwide.

Treatment:

Behavioral: Google ads

Reopen

Experimental group

Description:

The ad prompted people to get vaccinated to help Hong Kong reopen sooner.

Treatment:

Behavioral: Google ads