Addressing Stress-induced Decision-making Bias in Parents for Promoting COVID-19 Vaccination Among Hong Kong Children: a Survey-based Experiment

Background: As major decision-maker for children's wellbeing, parents play a vital role in decisiding on a wide range of health-related issues including vaccination. Such decision-making process will be complicated by a great amount of psychosocial stressors emerging from the current pandemic. Stress can lead to various decision-making biases for children vaccination and subsequently lead to low vaccination intention amongst parents, which may hinder the progress for reaching herd immunity and end the COVID-19 pandemic. Effective risk communication intervention thus is in urgent need to address stress-induced decision-making biases for an upcoming COVID-19 vaccine for young children.

Aims: This study will investigate the interrelationships among parental perceived stress, and interpretive bias toward negative vaccine-related stimuli and and vaccination intention. In addition, this study will also conduct a survey experiment to develop positive affect-based messages and test its effect on correcting stress-induced biases in vaccination decision making among parents with high mental stress level.

Design and subjects: We aim to recruit parents aged 18 years or above with at least one child in our study. Participants will be recruited from our previous study through WhatsApp. Participants will be invited to read a list of vaccine-related news headlines with a mixture of positive and negative sentiments first. Then they will be asked to complete a series of assessment on their vaccination decision-making and intention. In the next phase, a survey-based experiment will be embedded in the online questionnaire to test the effect of risk communication interventions. Intervention messages will be designed based on previous qualitative study and literatures on positive psychology to simulate parents' positive mental images of COVID-19 vaccination consequences by using positive-affect visual stimuli.

Main outcome measures and analysis: Participants will be invited to complete a series of assessments through online questionnaire to assess their mental stress level, negative interpretive bias on processing ambiguous vaccine information and behavioural intention for vaccinating children.

Paired t-test will be used to determine negative interpretive bias between high-stress vs. low-stress parents. Structural equation modelling (SEM) will be performed to test the relationships among parental mental stress level, affect-driven decision-making constructs and vaccination intention for children. For the survey-based experiment, the effect of positive-affect messages intervention on tendency of correcting decision-making biases and COVID-19 vaccine uptake for children will be evaluated using logistic regression model with perceived stress level and intervention as the main between-group factors.