Exploring the Effect of Video Interventions on Intentions for Continued COVID-19 Vaccination
Condition: Vaccine Refusal; COVID-19
MeSH terms: COVID-19
Study type: Interventional

Summary: 
      While COVID-19 vaccine uptake has generally been high in Canada, with 83.4% of the total
      population having received the first two doses (i.e., primary series), additional "booster"
      uptake has been slower, especially among young adults aged 18-39. Throughout the pandemic,
      young adults have experienced less personal risk from COVID-19 infection and this has led to
      lower motivation to vaccinate when it is recommended. Achieving high rates of up-to-date
      vaccine coverage is important in this group to anticipate new variants and waves of infection
      and changes to recommendations which might include annual or seasonal vaccination. Three
      video interventions, intended to motivate Canadian young adults to adopt positive intentions
      toward continued COVID-19 vaccination, will be developed and tested: an informational
      comparison video, an altruistic video, and an individualistic video. Participants will be
      3300 Canadian younger adults who will be randomly assigned to watch these videos. The first
      arm will only receive the informational video, the second arm the informational and
      altruistic videos, and the third arm the informational, altruistic, and individualistic
      videos. All participants will complete a brief online survey before and after viewing the
      assigned video(s). The goal of the study is to examine the efficacy of altruistic and
      individualistic messages, beyond informational messages, in increasing intentions for
      COVID-19 vaccination in this age group.
    

Detailed description: 
      The COVID-19 vaccine has significantly reduced mortality from the COVID-19 disease, and
      relieved the pressure on society, the economy, and the healthcare system caused by the
      pandemic. However, waning immunity and the emergence of new, vaccine-evasive variants like
      Omicron have necessitated additional vaccine doses, or "booster shots". Similar to trends for
      COVID-19 vaccination and other routine vaccinations, young adults (aged 18-39) have
      demonstrated lower uptake of booster vaccination, and evidence suggests that public health
      recommendations are no longer translating to vaccine uptake. This study will examine the
      efficacy of altruistic and individualistic messages over informational messages in increasing
      vaccine intentions in this age group.

      This study has four primary objectives:

        1. Estimate pre- to post-intervention changes in COVID-19 vaccine intentions of a
           altruistic video intervention.

        2. Estimate pre- to post-intervention changes in COVID-19 vaccine intentions of a combined
           altruistic + individualistic video

        3. Estimate between-group (altruistic vs. vaccine-informational) differences in COVID-19
           vaccine intentions post-intervention

        4. Estimate the between-group (altruistic + individualism vs. vaccine-informational)
           differences in COVID-19 vaccine intentions post-intervention

      In addition, there is an exploratory, multivariable objective:

      1. To estimate the multivariable associations of vaccine intentions in each intervention
      group.

      A survey will be administered online to a sample of Canadian residents, aged 18-39, in both
      English and French. Participants will be drawn from a database panel provided by Dynata, a
      multinational first-party data and insight platform. Dynata's use of Canadian census data
      from Statistics Canada and quota-based sampling will ensure that the sample will closely
      match the Canadian population in terms of age (18-29, 30-39), sex, first language
      English/French, population density (i.e., urban vs. rural), and household income. Dynata will
      send invitations in various forms (e.g., e-mail invitations, text messages and in-app alerts)
      to recruit eligible participants from their existing panel (individuals who have signed with
      Dynata and have expressed willingness to receive invitations to various appropriate surveys)
      until recruitment goals and quotas are met.

      To calculate the required sample size for the within-participant change in vaccine hesitancy
      (i.e., pre-post intervention) hesitancy towards continuing to receive booster vaccination was
      estimated at about 70% in the sample population. This estimate of the hesitancy rate at time
      of writing was based on seasonal influenza vaccination uptake in the target age range
      (between 20-25%) and uptake of COVID-19 booster vaccination in the past 6 months (9.2 -
      14.5%) accounting for a gradual increase in uptake observed over time. Informed by results of
      a previous two-arm RCT conducted by this research team (NCT04960228) that included a
      video-based intervention and an active control group, it is estimated that the intentions in
      the control group will increase from 30% to 33% and in the intervention groups from 30% to
      39%. To detect a 6% difference in intentions between arms, at a 95% confidence level (for a
      two-sided significance level α=0.025) and a desired statistical power of 80%, it was
      calculated that the minimum required number of participants per arm would be N=1005. 1:1:1
      randomization will be used the three between groups. Thus, one-third of the participants will
      be allocated to each intervention group. Including 95 additional participants per arm to
      account for possible inattentive responders, the total sample required for this study is 3300
      participants i.e., 1100 in each of the two experimental groups and 1100 in the active
      comparator group.

      Stratified randomization will be used for first language (English/French), sex (male/female),
      population density (Urban/rural) and household income (<$75,000 / >$75,000) to allocate
      participants to either intervention arm. Within each stratum, a random concept picker
      approach will be used to ensure a 1:1:1 allocation using groups of three participants.
      Correspondingly, the first participant of a group will be randomly allocated to one of the
      three study arms, the second randomly assigned to one of the two remaining arms, and the
      third to the remaining arm. If a participant does not finish the survey (incomplete data),
      that place in the group will be allocated to the next participant. Thus, the quota in each
      stratum will be filled in groups of three and ensure a balanced group allocation throughout
      data collection.

      The initial online survey will be approximately 12 minutes in length and will be available in
      both French and English. After reading the introductory statement of the study, participants
      will be asked for their consent to take part in the survey. Those who consent to participate
      will be invited to go to the next page and start completing the survey. Participants will
      first be asked to answer several socio-demographic questions and will be asked to choose
      their current Precaution Adoption Process Model stage for continued COVID-19 vaccination.
      Participants will then watch the assigned intervention. After viewing this content, to ensure
      that participants paid attention, participants will answer questions about the interventions
      to check their attention. Finally, participants will: 1) once again be asked to choose their
      vaccine decision-making stage; 2) be asked questions regarding previous vaccination history
      (e.g., seasonal influenza, COVID-19), lifestyle factors, self-perceived health status,
      personal history of SARS-CoV-2 infection, and preferred health-information channels; and 3)
      complete validated scales regarding, empathy, distress, intolerance of uncertainty,
      individualism and collectivism, COVID-19 pandemic fatigue, intellectual humility, and social
      desirability.

      To test within-participant outcomes (Objectives 1 and 2), McNemar's test will be used to
      compare paired (pre and post-intervention) proportions. Additionally, exact tests of symmetry
      comprising of multiple pairwise McNemar tests to estimate pre-post changes in vaccine
      intentions. Adjusted p values for multiple comparisons, odds ratios (OR) and Cohen's g effect
      sizes will be reported. For each study group, the significant transitions between vaccine
      intention stage pairs will be used for calculating the total number of participants that
      changed towards increased vaccination intentions (e.g., from undecided to decided to). To
      test between-group outcomes (Objectives 3 and 4), the Chi-square test will be used to examine
      differences in PAPM stage proportions between intervention groups.

      For the exploratory objective, Structural Equation Modelling will be used to identify
      multivariable associations of vaccine intentions (e.g., collectivism, empathy, intolerance of
      uncertainty) and to control for the potential effect of other factors (e.g.,
      sociodemographics, psychosocial factors, previous influenza vaccination, lifestyle factors).
    

Intervention name(s): Informational Video; Altruistic Video; Individualistic Video
Intervention type(s): Behavioral; Behavioral; Behavioral
Intervention description(s): This video emphasizes that vaccination against COVID-19 continues to be important, highlights the importance of seeking accurate information, and provides statistics about the estimated number of lives saved by vaccination and reported adverse events following vaccination in Canada.; This video presents a vignette about a young adult woman who has many social interactions during her daily life. It shows that her decision to stay up-to-date on COVID-19 vaccination could help to protect those people she comes into contact with, who may be at greater risk from COVID-19 infection. Statistics are used to show that up to one-in-four people in Canada have underlying conditions that make them more vulnerable to COVID-19, and to quantify the number of surgeries that were delayed by pandemic-related disruptions.; This video presents a vignette about a young adult man who is very health-conscious. He is unsure about staying up-to-date on COVID-19 vaccination until he learns that COVID-19 infection can have serious and disruptive consequences even if someone is younger. Statistics are used to quantify the increased risk of severe symptoms in young adults who are not up-to-date on vaccination.
Allocation: Randomized
Intervention model: Parallel Assignment
Intervention model description: Participants will be randomly assigned to one of: 1) a control video, 2) the control + an altruistic video, or 3) the control + altruistic video + individualistic video. A 1:1:1 randomization ratio will be used.
Masking: Single (Investigator)
Primary purpose: Prevention
Keywords: Vaccine Hesitancy; Vaccine Decision Making