Persuasion in Medicine: Experimental Evidence on Sender and Signal Effects

The aim of the study is to identify what sender/signal combinations are most persuasive in encouraging low socioeconomic males living in the U.S. to take-up seasonal flu vaccination. The investigators plan to recruit male subjects and randomly assign them to four persuasion treatments: three of which vary dimensions of the sender of a medical recommendation (racial concordance and authority treatments) and one which varies the signal (standard vs. empathetic). Specifically, the investigators will show subjects videos of either Black or white actors/actresses providing scripted information on the flu vaccination. The investigators will randomize the race of the sender and if the subject is Black, also randomize the authority of the sender, with the actor portraying either a doctor or a layperson. In addition, the investigators will vary the script used in the experiment between one that acknowledges past injustices (indicated as an empathetic script hereafter) and one that does not (indicated as a standard script hereafter). The investigators will provide subjects a free flu shot coupon and elicit the price at which subjects would be willing to give up this coupon for a cash reward. Lastly, in light of the relevance of vaccination take-up in combating COVID-19 pandemic, the investigators will assess demand for information about a COVID-19 vaccine, with subjects invited to receive results of a safety and efficacy review from a trusted or standard source. The design requires the collection of baseline and endline surveys combined with administrative data from pharmacies about coupon redemption. The primary outcomes of interest are posterior beliefs about seasonal flu vaccination, demand and willingness-to-pay (WTP) for a free flu shot coupon, redemption of the coupon, and demand for information about a COVID-19 vaccine.

Study Overview

• Status: Completed
• Conditions: Covid19; Influenza, Human; Flu, Human
• Intervention / Treatment: Behavioral: Video about safety and effectiveness of adult seasonal flu vaccination

Detailed Description

The investigators will recruit approximately 3350 African-American or Caucasian adult males with a high-school diploma or less. A pilot study, which ran during the 2019-20 flu season, recruited approximately 850 subjects, and a planned scale-up will recruit an additional 2500 subjects during the 2020-21 flu season. The investigators will oversample African American individuals, emphasizing low-income and minority men because these characteristics are correlated with lower relative take-up of flu vaccination. After informed consent is obtained, subjects will be asked about sociodemographic information (age, education, income and marital status), healthcare experience and past medical history, knowledge and beliefs about flu vaccination, and location of the nearest pharmacy. The investigators will then randomly assign the adult male subjects to videos which contain one of Black or white actors playing the role of either a doctor or a layperson as well as different scripts. The content of the infomercial will be the safety and effectiveness of adult seasonal flu vaccination. After the video, the investigators will obtain information on beliefs regarding vaccination, feedback on the video, attention to the video and willingness-to-pay for a flu shot coupon. The final baseline module will consist of a randomly assigned invitation to receive the results of an upcoming review of a COVID-19 vaccine, with subjects assigned to receive information from a trusted or standard source. The investigators will track flu coupon redemption, which is redeemable at most pharmacies nationwide.

• Study Type: Interventional
• Enrollment (Actual): 3245
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United States
  • Massachusetts
    • Cambridge, Massachusetts, United States, 02138
      • Harvard University

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 51 years (Adult)
• Accepts Healthy Volunteers: Yes
• Genders Eligible for Study: Male

Description

Inclusion Criteria:

• Age: See above.
• Education: Less than a college degree.
• Gender: Male.
• Race: Caucasian or African American.
• Miscellaneous: Has not received the flu shot in the current flu season yet.
• Miscellaneous: Has sound on his device turned on.

Exclusion Criteria:

• Fast survey-taking: subjects who are among the 5% fastest in terms of total time spent on survey within race and treatment group.
• Nonsense answers (those that do not have decipherable English) in the open text sections that suggest low effort.
• Inconsistent responses to questions (such as being willing to give up $10 to receive a flu coupon but not $1).
• Repeat survey takers as indicated by duplicate emails or IP addresses in survey data.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Health Services Research
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Double

Number of Arms

6

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Black R/Race C/Doctor/Standard Script; Video which contains a racially concordant actor playing a doctor and reading a standard script. The receiver of the message will be Black.	Behavioral: Video about safety and effectiveness of adult seasonal flu vaccination; The investigators will show subjects videos of either Black or white male actors providing scripted information on the flu vaccination. The content of the video will be the safety and effectiveness of adult seasonal flu vaccination. The videos contain one of Black or white actors playing the role of either a doctor or a layperson as well as different scripts.
Experimental: Black R/Race C/Layperson/Standard Script; Video which contains a racially concordant actor playing a layperson and reading a standard script. The receiver of the message will be Black.	Behavioral: Video about safety and effectiveness of adult seasonal flu vaccination; The investigators will show subjects videos of either Black or white male actors providing scripted information on the flu vaccination. The content of the video will be the safety and effectiveness of adult seasonal flu vaccination. The videos contain one of Black or white actors playing the role of either a doctor or a layperson as well as different scripts.
Experimental: Black R/Race D/Doctor/Standard Script; Video which contains a racially discordant actor playing a doctor and reading a standard script. The receiver of the message will be Black.	Behavioral: Video about safety and effectiveness of adult seasonal flu vaccination; The investigators will show subjects videos of either Black or white male actors providing scripted information on the flu vaccination. The content of the video will be the safety and effectiveness of adult seasonal flu vaccination. The videos contain one of Black or white actors playing the role of either a doctor or a layperson as well as different scripts.
Experimental: Black R/Race D/Doctor/Acknowledgement Script; Video which contains a racially discordant actor playing a doctor and reading an acknowledgement script. The receiver of the message will be Black.	Behavioral: Video about safety and effectiveness of adult seasonal flu vaccination; The investigators will show subjects videos of either Black or white male actors providing scripted information on the flu vaccination. The content of the video will be the safety and effectiveness of adult seasonal flu vaccination. The videos contain one of Black or white actors playing the role of either a doctor or a layperson as well as different scripts.
Experimental: White R/Race C/Doctor/Standard Script; Video which contains a racially concordant actor playing a doctor and reading a standard script. The receiver of the message will be White.	Behavioral: Video about safety and effectiveness of adult seasonal flu vaccination; The investigators will show subjects videos of either Black or white male actors providing scripted information on the flu vaccination. The content of the video will be the safety and effectiveness of adult seasonal flu vaccination. The videos contain one of Black or white actors playing the role of either a doctor or a layperson as well as different scripts.
Experimental: White R/Race D/Doctor/Standard Script; Video which contains a racially discordant actor playing a doctor and reading a standard script. The receiver of the message will be White.	Behavioral: Video about safety and effectiveness of adult seasonal flu vaccination; The investigators will show subjects videos of either Black or white male actors providing scripted information on the flu vaccination. The content of the video will be the safety and effectiveness of adult seasonal flu vaccination. The videos contain one of Black or white actors playing the role of either a doctor or a layperson as well as different scripts.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Rating of Sender	This is an inverse-covariance-weighted index comprised of responses to survey questions regarding: whether the respondent was interested in further medical advice from the given sender (measured as a binary outcome);; whether the respondent trusted advice from the sender measured on a scale of 1 to 5;; and whether the respondent's assessment of the sender's qualification to provide medical advice measured on a scale of 1 to 5. It is standardized to a mean of 0 and standard deviation of 1. Scores less than 0 indicate lower ratings of the sender rated by participants in Arm A (described in each arm/group description) compared to the rating rated by participants in Arm B (also described in each arm/group description). Scores greater than 0 indicate higher ratings of the sender by Arm A compared to by Arm B. For example, an index score of .18 indicates that participants in Arm A rate the sender 0.18 index (in standard deviation units) higher than those in Arm B.	This outcome was assessed during Baseline survey, which took approximately 20 minutes.
Rating of Signal	This is an inverse-covariance-weighted index comprised of responses to survey questions on: recommending the video to friends and family measured on a scale of 0 to 10;; recommending the flu shot to friends and family measured on a scale of 0 to 10;; and the respondent's assessment of the extent to which the information contained in the video was useful measured on a scale of 1 to 5. It is standardized to a mean of 0 and standard deviation of 1. An index score of 0 is equal to the mean. Scores less than 0 indicate lower ratings of the signal rated by participants in Arm A (described in each arm/group description) compared to the rating rated by participants in Arm B (also described in each arm/group description). Scores greater than 0 indicate higher ratings of the signal by Arm A compared to by Arm B. For example, an index score of 0.14 indicates that participants in Arm A rate the signal 0.14 index (in standard deviation units) higher than those in Arm B.	This outcome was assessed during Baseline survey, which took approximately 20 minutes.
Signal Content Recall	This is an inverse-covariance-weighted index comprised of responses to survey questions on: whether age group for whom the flu vaccine is recommended (measured as a binary outcome); and; whether the flu shot contains the flu virus (recall of information discussed in the video) (measured as a binary outcome). It is standardized to a mean of 0 and standard deviation of 1. An index score of 0 is equal to the mean. Scores less than 0 indicate lower level of recalling signal content among participants in Arm A (described in each arm/group description) compared to the level among participants in Arm B (also described in each arm/group description). Scores greater than 0 indicate a higher level of recalling signal content among participants in Arm A compared to those in Arm B. For example, an index score of 0.02 indicates that participants in Arm A recall signal content 0.02 index (in standard deviation units) higher than those in Arm B.	This outcome will be assessed during Baseline survey, which takes approximately 20 minutes.
Safety Beliefs	This is an inverse-covariance-weighted index comprised of: the point belief on the likelihood to contract the flu from the flu shot measured by a Likert scale and rescaled to have a support of -1 to 1.; the certainty measured with a balls and bins method and rescaled to have a support of -1 to 1. It is standardized to a mean of 0 and standard deviation of 1. An index score of 0 is equal to the mean. Scores less than 0 indicate a lower level of beliefs in the safety of flu vaccine among participants in Arm A (described in each arm/group description) compared to the level among participants in Arm B (also described in each arm/group description). Scores greater than 0 indicate a higher level of beliefs among participants in Arm A compared to those in Arm B. For example, an index score of -0.1 indicates that participants in Arm A hold such beliefs 0.1 index (in standard deviation units) lower than those in Arm B.	This outcome will be assessed during Baseline survey, which takes approximately 20 minutes.
Coupon Interest	This is an inverse-covariance-weighted index comprised of revealed preference measures of demand for a free flu shot coupon: Willingness to pay (WTP) for the coupon measured as $0, $1, $2, $5, or $10; demand for information regarding locations to redeem the coupon measured as a binary outcome It is standardized to a mean of 0 and standard deviation of 1. An index score of 0 is equal to the mean. Scores less than 0 indicate a lower level of interest in a free flu shot coupon distributed after survey completion among participants in Arm A (described in each arm/group description) compared to the level among participants in Arm B (also described in each arm/group description). Scores greater than 0 indicate a higher level of interest among participants in Arm A compared to those in Arm B. For example, an index score of -0.01 indicates that participants in Arm A hold such interest -0.01 index (in standard deviation units) higher than those in Arm B.	This outcome was assessed during Baseline survey, which took approximately 20 minutes.
(Posterior) Flu Vaccine Intent	This is the respondent's likelihood to receive the flu vaccine before the end of the flu season. This was elicited on an 11-point Likert scale (0 extremely unwilling, 10 extremely willing) after the video message treatment. We re-scaled this outcome to have a scale of 0 to 1. The reported results of the outcome compare participants in Arm A and Arm B (described in each arm/group description). For example, an intent of 0.03 indicates that participants in Arm A are 0.03 units on a scale more likely to intent to take up the flu vaccine compared to those in Arm B.	This outcome was assessed after the video treatment during Baseline survey, which took approximately 20 minutes.
COVID-19 Vaccine Intent	This is the respondent's likelihood to take up the COVID-19 vaccine if made available free of charge. This was elicited on an 11-point Likert scale (0 extremely unwilling, 10 extremely willing) after the video message treatment. We re-scaled this outcome to have a scale of 0 to 1. The reported results of the outcome compare participants in Arm A and Arm B (described in each arm/group description). For example, an intent of 0.04 indicates that participants in Arm A are 0.04 units on a scale more likely to intent to take up the COVID-19 vaccine compared to those in Arm B.	This outcome was assessed after the video treatment during Baseline survey, which took approximately 20 minutes.
Flu Vaccine Take-up	This is respondents' self-report in the follow-up survey on whether they or their family members had received the flu shot or redeemed the coupon since the intervention. The reported results of the outcome compare participants in Arm A and Arm B (described in each arm/group description). For example, 15.0 percentage points indicate that participants in Arm A are more likely to report that they and/or another household member received the flu vaccine by 15.p percentage points compared to those in Arm B.	This outcome was assessed during the follow-up survey which was conducted at least two weeks after the initial baseline survey.

Collaborators and Investigators

• Sponsor: Harvard University
• Collaborators: National Institute on Aging (NIA); Massachusetts Institute of Technology; Ludwig-Maximilians - University of Munich

Study record dates

Study Major Dates

• Study Start (Actual): December 20, 2019
• Primary Completion (Actual): February 19, 2021
• Study Completion (Actual): February 19, 2021

Study Registration Dates

• First Submitted: November 8, 2019
• First Submitted That Met QC Criteria: November 9, 2019
• First Posted (Actual): November 13, 2019

Study Record Updates

• Last Update Posted (Actual): June 29, 2021
• Last Update Submitted That Met QC Criteria: June 26, 2021
• Last Verified: June 1, 2021

More Information

Terms related to this study

• Keywords: Preventive Care; Belief Updating; Racial Disparity
• Additional Relevant MeSH Terms: RNA Virus Infections; Virus Diseases; Infections; Respiratory Tract Infections; Respiratory Tract Diseases; Orthomyxoviridae Infections; Influenza, Human
• Other Study ID Numbers: IRB19-1424

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No