Influence of social norms on attitudes towards COVID-19 vaccination

We investigate whether providing citizens with representative information about the vaccination intentions of adults in Germany affects their intention to get the COVID-19-vaccine. Therefore, we plan to run an information provision experiment, where we provide respondents with information about social norms.
After eliciting beliefs about the social norm, we provide one group of participants with information about the norm, elicited in a prior survey, while the control group gets no additional information. Afterward we ask several questions concerning the respondents readiness to get vaccinated against COVID-19 as well as other vaccine-related questions.

Subjects will conduct the experiment via an online platform.
Subjects will be randomly assigned to one of two experimental groups, and each subject takes decisions in four consecutive stages.
Respondents of both groups got following information before they answered Q00.
“From March 24 to April 2, 2021, a similar survey was conducted with people aged 18 to 69. These respondents were selected to represent the overall population in Germany as closely as possible.”

Survey — [Question wording:]

Stage 1: Beliefs about social norms

[Q00] “Estimation question: What do you estimate is the percentage of respondents who agree with the following statement?”

“To what extent do you agree with the following statement?
"I will get vaccinated against COVID-19 as soon as a vaccine is available for me."
(Assume that the vaccination is free. If you have already been vaccinated, please put yourself in the situation as if you have not yet been vaccinated)”

____ out of 100 respondents agree "strongly" or "somewhat" with the statement.
[Answer categories:]
Open answer – number from 0-100.

 
Stage 2: Index: Intention to vaccinate, WTP, and injunctive norm

[Q01]: To what extent do you agree with the following statement?
"I will get vaccinated against COVID-19 as soon as a vaccine is available for me."
(Assume that the vaccination is free. If you have already been vaccinated, please put yourself in the situation as if you have not yet been vaccinated)
[Answer categories:]
5-point scale: 1: “I fully agree”, 2: “I rather agree”, 3: “I rather disagree”,
4: “I do not agree at all”, 5: “Neither”

[Q02]: To what extent do you agree with the following statement?
"People should get vaccinated against COVID-19 as soon as a vaccine is available."
[Answer categories:]
5-point scale: 1: “I fully agree”, 2: “I rather agree”, 3: “I rather disagree”,
4: “I do not agree at all”, 5: “Neither”

[Q03] “Estimation question: In the survey from March 24 to April 2, 2021, what do you estimate is the percentage of respondents who agree with the following statement?”

To what extent do you agree with the following statement?
"People should get vaccinated against COVID-19 as soon as a vaccine is available."

____ out of 100 respondents agree "strongly" or "somewhat" with the statement.

[Answer categories:]
Open answer – number from 0-100.

[Q03s] “How confident are you that your answer is approximately correct?”
[Answer categories:]
7-point scale: 1: “Very uncertain”, … , 7: “Very certain”

 
[Q04] To what extent do you agree with the following statement?
"If I could choose the vaccine myself, I would get vaccinated against COVID-19 as soon as a vaccination is available for me.”
(If you have already been vaccinated, please put yourself in the situation as if you have not yet been vaccinated).
[Answer categories:]
5-point scale: 1: “I fully agree”, 2: “I rather agree”, 3: “I rather disagree”,
4: “I do not agree at all”, 5: “Neither”


[Q05] Now it's a question of how much a vaccination against COVID-19 would be worth to you: What is the most you would be willing to pay to be vaccinated tomorrow with the vaccine of your choice?
(State the most you would pay out of your own pocket if the vaccine were available for you to buy. Please indicate "0" euros if you do not want to be vaccinated. If you have already been vaccinated, please put yourself in the situation as if you had not yet been vaccinated.)
____ Euro
[Answer categories:]
Open answer – number.

[Q06] And what is the most you would be willing to pay to have a person of your choice (not you) vaccinated tomorrow with the vaccine of your choice?
(State the most you would pay out of your own pocket if the vaccine were available for you to buy. Please indicate "0" euros if you do not want another person of your choice to be vaccinated.)
____ Euro
[Answer categories:]
Open answer – number
 
[Q07] Would you like to receive a link at the end of this survey to pre-register for a COVID-19 vaccination?
[Answer categories:]
2-point scale: 1: “Yes”,
3: “No”

[If Q07 = “No”] [Q07f] Have you already registered for the COVID-19 vaccination?

[Answer categories:]
2-point scale: 1: “Yes”,
3: “No”


[Q08] To what extent do you agree with the following statement?
"If I had the chance, I would get vaccinated tomorrow…”
(If you have already been vaccinated, please put yourself in the situation as if you have not yet been vaccinated).
[…i1] “…. with the BioNTech and Pfizer vaccine.”
[…i2] “…. with the AstraZeneca vaccine.”

[note that we randomize the order of the two questions. This randomization is independent of the treatment-randomization.]

[Answer categories:]
5-point scale: 1: “I fully agree”, 2: “I rather agree”, 3: “I rather disagree”,
4: “I do not agree at all”, 5: “Neither”


Stage 3: other Index variables + Moderators and Mediators

[Q09…] To what extent do you agree with the following statement?
[…i1] " I believe that the majority of my closest relatives and acquaintances will be vaccinated against COVID-19.”
[…i2] " I think my closest relatives and acquaintances expect me to get vaccinated against COVID-19.”
[…i3] " Society expects me to get vaccinated against COVID-19.”
[…i4] " It is better for me if I get vaccinated against COVID-19.”
[…i5] " It is better for my relatives and acquaintances if I get vaccinated against COVID-19.”
[…i6] " It is better for society if I get vaccinated againstCOVID-19.”
[…i7] " I have full confidence in COVID-19 vaccination.”


[Answer categories:]
5-point scale: 1: “I fully agree”, 2: “I rather agree”, 3: “I rather disagree”,
4: “I do not agree at all”, 5: “Neither”


[Q10] To what extent do you agree with the following statement?
[…i1] "All in all, I feel well informed about COVID-19 vaccination.”
[…i2] "If many others get vaccinated, then I will get vaccinated too.”
[…i3] "I would like to get vaccinated only after I have seen that others have not experienced severe side effects.”
[…i4] "If many others have been vaccinated against COVID-19, I don't need to get vaccinated too.”
[…i5] " The expectation of my relatives and acquaintances is important for my own vaccination decision.”
[…i6] "I am in favour of vaccinated people receiving legal benefits (e.g., being allowed to go to restaurants or fly without testing).”
[…i7] "I am in favour of punishing people who refuse COVID-19 vaccination (e.g., by restricting their freedom to travel or banning them from certain professions).”
[…i8] "I recommend that other individuals be vaccinated against COVID-19.”
[…i9] "COVID-19 vaccination should be mandatory for everyone.”




Stage 4 & 5: Personal questions & time-, risk-, and social preferences
 
[Treatment Variation]
As explained above, we provide different information to different groups between
stage 1 and stage 2:
[Treatment 1] — no Information
[Treatment 2] — Information about descriptive social norm in Germany from a previous survey

In the survey from March 24 to April 2, 2021, 70 of 100 respondents agreed with the statement: "I will get vaccinated against COVID-19 as soon as a vaccine is available for me.".
[pie chart - descriptive norm]

Participants in Treatment 2 will see the following information during stage 2 and stage 3:
As a reminder, 70 of 100 respondents agreed with the statement "I will get vaccinated against COVID-19 as soon as a vaccine is available for me.".

2021-04-09

2021-05-20

Intention to get vaccinated (5 outcomes), willingness to pay for the vaccine (2 outcomes), and normative social norm (2 outcomes). In our main analysis, we will create summary indices of these outcomes and estimate treatment effects on these indices. We will also investigate treatment effects on individual outcomes.

Heterogeneity by prior beliefs; treatment effects on mediators and moderators (Q8 and Q9).

We plan to sample a minimum of 2,000 adults aged between 18 and 69 years (up to a maximum of 3,000 — conditional on pending supplementary research funding; also see “Experiment characteristics”).
The survey is conducted in cooperation with a survey institute. The recruitment and polling are managed by the survey institute, which collects the data via an online platform. That is, our participants answer the survey questions autonomously on their own digital devices. Randomization is carried out by the survey institute at the individual level, using a computer.
Our experiment is structured as follows:
Respondents will be randomly assigned (between subject) to
Treatment 1 (p=0.5), or Treatment 2 (p=0.5).

Treatment 1:
Stage 1: Beliefs about social norms
[no Information-provision]
Stage 2: Intention to vaccinate — Index
Stage 3: Moderators and Mediators
Stage 4: Personal Questions & Time-, risk-, and social preferences


Treatment 2:
Stage 1: Beliefs about social norms
[Information about descriptive norm]
Stage 2: Intention to vaccinate — Index [+ info: descriptive norm]
Stage 3: Moderators and Mediators [+ info: descriptive norm]
Stage 4: Personal Questions & Time-, risk-, and social preferences

(e.g. public lottery, randomization done in office by a computer, coin flip): Randomization is carried out by the survey company, using a computer.

at the individual level

No

2,000 individuals (adults aged between 18 and 69 years). (maximum: 3,000 – conditional on pending supplementary research funding)

2,000 individuals (1,000 per treatment). (maximum: 3,000 (1,500/1,500) – conditional on pending supplementary research funding). According to our conservative cost calculations, we have sufficient funding for sampling 2,000 individuals. In case that we are granted supplementary research funding, we envisage to continue sampling up to a maximum number of 3,000 individuals.

1,000 per treatment (maximum 1,500/1,500 - conditional on pending supplementary research funding)