Views on COVID-19 and Vaccination

• Sponsor: University of Massachusetts, Worcester (Other)
• Overall Status: Completed
• CT.gov ID: NCT04706403
• Collaborator: National Library of Medicine (NLM) (NIH)
• Enrollment: 756
• Location: 1
• Arms: 5
• Actual Duration (Days): 20
• Patients Per Site Per Month: 1150.5

Study Details

Study Description

Brief Summary

The goal of this study is to develop evidence-based messages that effectively mitigate concerns of people at risk for not being vaccinated against COVID-19, with the ultimate goal of maximizing vaccine uptake in vulnerable populations. The investigators will collect data on COVID-19 disease and vaccine knowledge, beliefs, and intent to be vaccinated from an existing online panel. Results from this data collection will be used to develop effective messages and communication strategies. The investigators will test alternate versions of messages intended to reduce vaccine hesitancy and promote vaccine uptake among vaccine-hesitant individuals. This project will ultimately result in a set of tested, evidence-derived messages about vaccination for COVID-19.

Condition or Disease	Intervention/Treatment	Phase
Covid19	Behavioral: Communication from a physician about the COVID-19 Vaccine	N/A

Detailed Description

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has rapidly instigated a global pandemic. As of this writing, there are approximately 65 million documented cases of infection worldwide, and over 1.5 million deaths. In the United States (US), coronavirus disease 2019 (COVID-19) has disrupted the economy, overwhelmed healthcare system, led to widespread school cancellations, and caused more than 274,000 deaths since March 2020. A vaccine against COVID-19 is widely viewed as the key to controlling the pandemic and enabling a return to "normal" life. Vaccine development is proceeding at an unprecedented pace with 10 vaccines currently in phase 3 trials. Experts have projected that a safe and effective vaccine may be available by mid-2021. At the same time, a growing body of evidence indicates that a significant proportion of adults in the U.S. may not accept vaccination against COVID-19. Even more alarming, COVID-19 vaccine hesitancy (refusal or reluctance to accept a vaccine) appears to be increasing as the vaccine approval process becomes increasingly politicized. Just as efforts to develop vaccine production and delivery capacity have been undertaken in advance of having a proven effective vaccine, parallel efforts are needed to identify effective messages and communication strategies to overcome COVID-19 vaccine hesitancy.

The study team recently surveyed a nationally representative sample of approximately 1,000 adults in the United States and found that only 57% intended to be vaccinated when a coronavirus vaccine becomes available. This percentage was even lower among people who identified as Black or Hispanic (39% and 43% respectively), those with a high school education or less (46%), and those in the lowest income groups (49% of those reporting a household income of $30,000 or less, compared to 72% of those reporting a household income of $100,000 or more). The investigators asked those who indicated they would not or might not get vaccinated for their reasons and found that some individuals may be willing to be vaccinated if provided specific information about the vaccine such as side effects and effectiveness. Others expressed generalized skepticism, fear, and distrust of vaccines, with some even referring to anti-vaccine conspiracy theories. These findings are consistent with an extensive body of research documenting that people often do not behave rationally and highlight the urgent need to proactively develop and test interventions to maximize vaccination rates when a coronavirus vaccine becomes available. To address this need, in the present study, the investigators aim to create and test targeted messages to address the concerns of subgroups of people at risk for not being vaccinated, with the ultimate goal of maximizing vaccine uptake when a vaccine for COVID-19 becomes available. The investigators will accomplish this by working with an existing online panel of volunteers, which will allow efficient, focused data gathering. Results of the survey will provide a nuanced, current description of how vulnerable adults perceive the coronavirus and available vaccines, which will be used as the basis for developing messages and communication strategies. Participants will be randomized to receive one of five different versions of a message from a healthcare provider regarding vaccination. Specific wording and content of these messages will vary systematically in order to address concerns of those at risk for not being vaccinated. This project will ultimately result in a set of tested, evidence-derived messages about vaccination for COVID-19. The investigators will make these messages available, together with evidence of how these influence members of vulnerable populations' understanding of vaccination, and disease risk, as well as intent to be vaccinated. The messages will be freely available for use by organizations and providers seeking to improve communication about a coronavirus vaccine.

Study Design

• Study Type: Interventional
• Actual Enrollment: 756 participants
• Allocation: Randomized
• Intervention Model: Parallel Assignment
• Masking: None (Open Label)
• Primary Purpose: Prevention
• Official Title: If We Build It, Will They Come? A Pilot Study to Develop and Test Messages to Maximize Uptake of Coronavirus Vaccine When Available
• Actual Study Start Date: Jan 12, 2021
• Actual Primary Completion Date: Feb 1, 2021
• Actual Study Completion Date: Feb 1, 2021

Arms and Interventions

Arm	Intervention/Treatment
Experimental: Message 1 Participants were randomized to receive version #1 of 5 different versions of a message from a physician regarding the COVID-19 vaccination. All messages included a statement that the vaccine is very safe and very effective. In Message 1, this statement was followed by a participatory-style recommendation ("What do you think?")	Behavioral: Communication from a physician about the COVID-19 Vaccine; Participants who expressed hesitation about getting vaccinated against COVID-19 were randomized to receive one of five different versions of messages from a physician. The messages that participants in each group received varied slightly and systematically. Specific content and wording of these messages were developed to address and mitigate concerns of those at risk for not being vaccinated.
Experimental: Message 2 Participants were randomized to receive version #2 of 5 different versions of a message from a physician regarding vaccination. All messages included a statement that the vaccine is very safe and very effective. In Message 2, this statement was followed by a comparison of the COVID-19 vaccine to the flu shot and an explicit recommendation ("I recommend that you get it").	Behavioral: Communication from a physician about the COVID-19 Vaccine; Participants who expressed hesitation about getting vaccinated against COVID-19 were randomized to receive one of five different versions of messages from a physician. The messages that participants in each group received varied slightly and systematically. Specific content and wording of these messages were developed to address and mitigate concerns of those at risk for not being vaccinated.
Experimental: Message 3 Participants were randomized to receive version #3 of 5 different versions of a message from a physician regarding vaccination. All messages included a statement that the vaccine is very safe and very effective. In Message 3, this statement was followed by a statement that millions of people have already received the COVID-19 vaccine and an explicit recommendation ("I recommend that you get it").	Behavioral: Communication from a physician about the COVID-19 Vaccine; Participants who expressed hesitation about getting vaccinated against COVID-19 were randomized to receive one of five different versions of messages from a physician. The messages that participants in each group received varied slightly and systematically. Specific content and wording of these messages were developed to address and mitigate concerns of those at risk for not being vaccinated.
Experimental: Message 4 Participants were randomized to receive version #4 of 5 different versions of a message from a physician regarding vaccination. All messages included a statement that the vaccine is very safe and very effective. In Message 4, this statement was followed by an acknowledgment of concerns and reassurance that the physician personally reviewed the safety data and an explicit recommendation ("I recommend that you get it").	Behavioral: Communication from a physician about the COVID-19 Vaccine; Participants who expressed hesitation about getting vaccinated against COVID-19 were randomized to receive one of five different versions of messages from a physician. The messages that participants in each group received varied slightly and systematically. Specific content and wording of these messages were developed to address and mitigate concerns of those at risk for not being vaccinated.
Experimental: Message 5 Participants were randomized to receive version #5 of 5 different versions of a message from a physician regarding vaccination. All messages included a statement that the vaccine is very safe and very effective. In Message 5, this statement was followed by an emphasis on protecting others an explicit recommendation ("I recommend that you get it").	Behavioral: Communication from a physician about the COVID-19 Vaccine; Participants who expressed hesitation about getting vaccinated against COVID-19 were randomized to receive one of five different versions of messages from a physician. The messages that participants in each group received varied slightly and systematically. Specific content and wording of these messages were developed to address and mitigate concerns of those at risk for not being vaccinated.

Outcome Measures

Primary Outcome Measures

1. Number of Participants Who Became Less Hesitant About the COVID-19 Vaccine After Receiving a Physician Message [Through survey completion, an average of 12 minutes]

   All participants were asked about their intent to be vaccinated against COVID-19 prior to exposure to one of the five physician messages (Response options: Yes, No, Not sure). After participants were randomly assigned to receive one of the five physician messages, reduction in COVID-19 vaccine hesitancy was assessed with the question: "Would you get vaccinated at this visit". Response options included yes, no, not sure. For participants whose initial vaccination intent was "not sure", a response of "yes" on re-assessment was defined as less hesitant. Response of "not sure" or "yes" were defined as less hesitant for participants whose initial vaccination intent was "no".

Eligibility Criteria

Criteria

• Ages Eligible for Study: 18 Years and Older
• Sexes Eligible for Study: All
• Accepts Healthy Volunteers: No

Inclusion Criteria:

• Adult (age 18 and over) who are members of an online panel (Prolific). Members of this panel joined the panel specifically to receive invitations to participate in research surveys and similar activities.

• Able to complete an online survey in English.

Exclusion Criteria:

• None

Contacts and Locations

Locations

	Site	City	State	Country	Postal Code
1	Meyers Health Care Institute	Worcester	Massachusetts	United States	01605

Sponsors and Collaborators

• University of Massachusetts, Worcester
• National Library of Medicine (NLM)

Investigators

• Principal Investigator: Kimberly Fisher, MD, University of Massachusetts, Worcester

Study Documents (Full-Text)

• Study Protocol and Statistical Analysis Plan - Jan 15, 2021

More Information

Publications

• Brewer NT, Chapman GB, Rothman AJ, Leask J, Kempe A. Increasing Vaccination: Putting Psychological Science Into Action. Psychol Sci Public Interest. 2017 Dec;18(3):149-207. doi: 10.1177/1529100618760521.
• Fisher KA, Bloomstone SJ, Walder J, Crawford S, Fouayzi H, Mazor KM. Attitudes Toward a Potential SARS-CoV-2 Vaccine : A Survey of U.S. Adults. Ann Intern Med. 2020 Dec 15;173(12):964-973. doi: 10.7326/M20-3569. Epub 2020 Sep 4.
• Godinho CA, Yardley L, Marcu A, Mowbray F, Beard E, Michie S. Increasing the intent to receive a pandemic influenza vaccination: Testing the impact of theory-based messages. Prev Med. 2016 Aug;89:104-111. doi: 10.1016/j.ypmed.2016.05.025. Epub 2016 May 25.
• Mowbray F, Marcu A, Godinho CA, Michie S, Yardley L. Communicating to increase public uptake of pandemic flu vaccination in the UK: Which messages work? Vaccine. 2016 Jun 14;34(28):3268-74. doi: 10.1016/j.vaccine.2016.05.006. Epub 2016 May 8.
• Nowak GJ, Sheedy K, Bursey K, Smith TM, Basket M. Promoting influenza vaccination: insights from a qualitative meta-analysis of 14 years of influenza-related communications research by U.S. Centers for Disease Control and Prevention (CDC). Vaccine. 2015 Jun 4;33(24):2741-56. doi: 10.1016/j.vaccine.2015.04.064. Epub 2015 Apr 28. Review.
• Redelings MD, Piron J, Smith LV, Chan A, Heinzerling J, Sanchez KM, Bedair D, Ponce M, Kuo T. Knowledge, attitudes, and beliefs about seasonal influenza and H1N1 vaccinations in a low-income, public health clinic population. Vaccine. 2012 Jan 5;30(2):454-8. doi: 10.1016/j.vaccine.2011.10.050. Epub 2011 Oct 30.

• Responsible Party: Kimberly Fisher, Associate Professor, University of Massachusetts, Worcester
• ClinicalTrials.gov Identifier: NCT04706403
• Other Study ID Numbers: H00022244
• First Posted: Jan 12, 2021
• Last Update Posted: May 24, 2022
• Last Verified: May 1, 2022

• Individual Participant Data (IPD) Sharing Statement: No
• Plan to Share IPD: No
• Studies a U.S. FDA-regulated Drug Product: No
• Studies a U.S. FDA-regulated Device Product: No
• Keywords provided by Kimberly Fisher, Associate Professor, University of Massachusetts, Worcester: Covid-19; Vaccination
• Additional relevant MeSH terms: COVID-19

Study Results

Participant Flow

Recruitment Details

Participants were recruited on Prolific.co from 01/12/21-02/01/21. Eligible panel members were >= 18, English speaking, and U.S residents. Panel members were restricted to include White, Black, or Hispanic; Blacks and Hispanics were oversampled. Participants who responded "no" or "not sure" to "If you could get vaccinated for COVID-19 today, would you?" were classified as vaccine hesitant and randomized to receive 1 of 5 physician messages, after which their intent was reassessed.

Arm/Group Title	Message 1	Message 2	Message 3	Message 4	Message 5
Arm/Group Description	Participants were randomized to receive version #1 of 5 different versions of a message from a physician regarding the COVID-19 vaccination. All messages included a statement that the vaccine is very safe and very effective. In Message 1, this statement was followed by a participatory-style recommendation ("What do you think?")	Participants were randomized to receive version #2 of 5 different versions of a message from a physician regarding vaccination. All messages included a statement that the vaccine is very safe and very effective. In Message 2, this statement was followed by a comparison of the COVID-19 vaccine to the flu shot and an explicit recommendation ("I recommend that you get it").	Participants were randomized to receive version #3 of 5 different versions of a message from a physician regarding vaccination. All messages included a statement that the vaccine is very safe and very effective. In Message 3, this statement was followed by a statement that millions of people have already received the COVID-19 vaccine and an explicit recommendation ("I recommend that you get it").	Participants were randomized to receive version #4 of 5 different versions of a message from a physician regarding vaccination. All messages included a statement that the vaccine is very safe and very effective. In Message 4, this statement was followed by an acknowledgment of concerns and reassurance that the physician personally reviewed the safety data and an explicit recommendation ("I recommend that you get it").	Participants were randomized to receive version #5 of 5 different versions of a message from a physician regarding vaccination. All messages included a statement that the vaccine is very safe and very effective. In Message 5, this statement was followed by an emphasis on protecting others an explicit recommendation ("I recommend that you get it").
Period Title: Overall Study
STARTED	172	121	165	146	152
COMPLETED	172	121	164	145	150
NOT COMPLETED	0	0	1	1	2

Baseline Characteristics

Arm/Group Title	Message 1	Message 2	Message 3	Message 4	Message 5	Total
Arm/Group Description	Participants were randomized to receive version #1 of 5 different versions of a message from a physician regarding the COVID-19 vaccination. All messages included a statement that the vaccine is very safe and very effective. In Message 1, this statement was followed by a participatory-style recommendation ("What do you think?")	Participants were randomized to receive version #2 of 5 different versions of a message from a physician regarding vaccination. All messages included a statement that the vaccine is very safe and very effective. In Message 2, this statement was followed by a comparison of the COVID-19 vaccine to the flu shot and an explicit recommendation ("I recommend that you get it").	Participants were randomized to receive version #3 of 5 different versions of a message from a physician regarding vaccination. All messages included a statement that the vaccine is very safe and very effective. In Message 3, this statement was followed by a statement that millions of people have already received the COVID-19 vaccine and an explicit recommendation ("I recommend that you get it").	Participants were randomized to receive version #4 of 5 different versions of a message from a physician regarding vaccination. All messages included a statement that the vaccine is very safe and very effective. In Message 4, this statement was followed by an acknowledgement of concerns and reassurance that the physician personally reviewed the safety data and an explicit recommendation ("I recommend that you get it").	Participants were randomized to receive version #5 of 5 different versions of a message from a physician regarding vaccination. All messages included a statement that the vaccine is very safe and very effective. In Message 5, this statement was followed by an emphasis on protecting others an explicit recommendation ("I recommend that you get it").	Total of all reporting groups
Overall Participants	172	121	164	145	150	752
Age, Customized (Count of Participants)
Less than 24 years	43 25%	31 25.6%	37 22.6%	38 26.2%	41 27.3%	190 25.3%
25 - 34 years	40 23.3%	32 26.4%	42 25.6%	28 19.3%	42 28%	184 24.5%
35 - 44 years	50 29.1%	27 22.3%	31 18.9%	50 34.5%	33 22%	191 25.4%
45 - 54 years	22 12.8%	21 17.4%	27 16.5%	17 11.7%	20 13.3%	107 14.2%
55 - 64 years	13 7.6%	4 3.3%	20 12.2%	10 6.9%	11 7.3%	58 7.7%
65 years or older	3 1.7%	5 4.1%	3 1.8%	2 1.4%	2 1.3%	15 2%
Missing	1 0.6%	1 0.8%	4 2.4%	0 0%	1 0.7%	7 0.9%
Sex/Gender, Customized (Count of Participants)
Male	62 36%	41 33.9%	71 43.3%	52 35.9%	65 43.3%	291 38.7%
Female	108 62.8%	78 64.5%	88 53.7%	93 64.1%	82 54.7%	449 59.7%
Other	0 0%	2 1.7%	4 2.4%	0 0%	0 0%	6 0.8%
Prefer not to say	1 0.6%	0 0%	0 0%	0 0%	0 0%	1 0.1%
Missing	1 0.6%	0 0%	1 0.6%	0 0%	3 2%	5 0.7%
Race/Ethnicity, Customized (Count of Participants)
Hispanic/Latino	35 20.3%	31 25.6%	41 25%	33 22.8%	37 24.7%	177 23.5%
Black/African American	79 45.9%	52 43%	66 40.2%	64 44.1%	65 43.3%	326 43.4%
White	58 33.7%	37 30.6%	57 34.8%	48 33.1%	48 32%	248 33%
Missing	0 0%	1 0.8%	0 0%	0 0%	0 0%	1 0.1%
Region of Enrollment (participants) [Number]
United States	172 100%	121 100%	164 100%	145 100%	150 100%	752 100%
Initial Vaccination Intent (Count of Participants)
Initially "No"	103 59.9%	66 54.5%	83 50.6%	78 53.8%	81 54%	411 54.7%
Initially "Not Sure"	69 40.1%	55 45.5%	81 49.4%	67 46.2%	69 46%	341 45.3%
Education (Count of Participants)
High School or Less	44 25.6%	40 33.1%	53 32.3%	38 26.2%	49 32.7%	224 29.8%
Some college	86 50%	56 46.3%	85 51.8%	70 48.3%	68 45.3%	365 48.5%
4-year college or more	42 24.4%	25 20.7%	25 15.2%	36 24.8%	32 21.3%	160 21.3%
Missing	0 0%	0 0%	1 0.6%	1 0.7%	1 0.7%	3 0.4%
Employment (Count of Participants)
Employed	88 51.2%	64 52.9%	83 50.6%	83 57.2%	76 50.7%	394 52.4%
Unemployed	30 17.4%	20 16.5%	29 17.7%	20 13.8%	30 20%	129 17.2%
Student	25 14.5%	15 12.4%	15 9.1%	19 13.1%	18 12%	92 12.2%
Homemaker	16 9.3%	12 9.9%	9 5.5%	14 9.7%	13 8.7%	64 8.5%
Disabled	6 3.5%	3 2.5%	10 6.1%	4 2.8%	5 3.3%	28 3.7%
Retired	3 1.7%	3 2.5%	7 4.3%	4 2.8%	4 2.7%	21 2.8%
Other	4 2.3%	3 2.5%	10 6.1%	1 0.7%	4 2.7%	22 2.9%
Missing	0 0%	1 0.8%	1 0.6%	0 0%	0 0%	2 0.3%
Household Income (Count of Participants)
Less than $30,000	47 27.3%	43 35.5%	55 33.5%	40 27.6%	57 38%	242 32.2%
$30,000 - $60,000	53 30.8%	41 33.9%	57 34.8%	51 35.2%	53 35.3%	255 33.9%
$60,000 - $100,000	44 25.6%	27 22.3%	35 21.3%	26 17.9%	27 18%	159 21.1%
More than $100,000	21 12.2%	7 5.8%	11 6.7%	19 13.1%	9 6%	67 8.9%
Prefer not to answer	6 3.5%	2 1.7%	5 3%	9 6.2%	3 2%	25 3.3%
Missing	1 0.6%	1 0.8%	1 0.6%	0 0%	1 0.7%	4 0.5%
Geographic region (Count of Participants)
South	90 52.3%	66 54.5%	80 48.8%	75 51.7%	80 53.3%	391 52%
Midwest	28 16.3%	17 14%	34 20.7%	31 21.4%	21 14%	131 17.4%
West	28 16.3%	21 17.4%	23 14%	15 10.3%	33 22%	120 16%
Northeast	26 15.1%	17 14%	27 16.5%	24 16.6%	16 10.7%	110 14.6%
History of flu shot (Count of Participants)
Ever, in the last 5 years	73 42.4%	40 33.1%	70 42.7%	78 53.8%	71 47.3%	332 44.1%
Not sure or no	99 57.6%	81 66.9%	93 56.7%	67 46.2%	79 52.7%	419 55.7%
Missing	0 0%	0 0%	1 0.6%	0 0%	0 0%	1 0.1%
Self-rated overall health (Count of Participants)
Excellent	22 12.8%	12 9.9%	13 7.9%	9 6.2%	13 8.7%	69 9.2%
Very good	44 25.6%	34 28.1%	48 29.3%	40 27.6%	39 26%	205 27.3%
Good	69 40.1%	51 42.1%	66 40.2%	58 40%	65 43.3%	309 41.1%
Fair	27 15.7%	19 15.7%	34 20.7%	33 22.8%	24 16%	137 18.2%
Poor	9 5.2%	5 4.1%	3 1.8%	5 3.4%	8 5.3%	30 4%
Missing	1 0.6%	0 0%	0 0%	0 0%	1 0.7%	2 0.3%
Self-rated overall mental health (Count of Participants)
Excellent	22 12.8%	17 14%	22 13.4%	12 8.3%	18 12%	91 12.1%
Very good	43 25%	31 25.6%	37 22.6%	33 22.8%	30 20%	174 23.1%
Good	42 24.4%	38 31.4%	48 29.3%	47 32.4%	50 33.3%	225 29.9%
Fair	51 29.7%	20 16.5%	39 23.8%	35 24.1%	40 26.7%	185 24.6%
Poor	14 8.1%	15 12.4%	18 11%	17 11.7%	12 8%	76 10.1%
Missing	0 0%	0 0%	0 0%	1 0.7%	0 0%	1 0.1%

Outcome Measures

1. Primary Outcome

Title	Number of Participants Who Became Less Hesitant About the COVID-19 Vaccine After Receiving a Physician Message
Description	All participants were asked about their intent to be vaccinated against COVID-19 prior to exposure to one of the five physician messages (Response options: Yes, No, Not sure). After participants were randomly assigned to receive one of the five physician messages, reduction in COVID-19 vaccine hesitancy was assessed with the question: "Would you get vaccinated at this visit". Response options included yes, no, not sure. For participants whose initial vaccination intent was "not sure", a response of "yes" on re-assessment was defined as less hesitant. Response of "not sure" or "yes" were defined as less hesitant for participants whose initial vaccination intent was "no".
Time Frame	Through survey completion, an average of 12 minutes

Outcome Measure Data

Analysis Population Description

Four participants were excluded from the analyses because they did not respond to the question re-assessing vaccination intent following exposure to a physician recommendation.

Arm/Group Title	Message 1	Message 2	Message 3	Message 4	Message 5
Arm/Group Description	Participants were randomized to receive version #1 of 5 different versions of a message from a physician regarding the COVID-19 vaccination. All messages included a statement that the vaccine is very safe and very effective. In Message 1, this statement was followed by a participatory-style recommendation ("What do you think?")	Participants were randomized to receive version #2 of 5 different versions of a message from a physician regarding vaccination. All messages included a statement that the vaccine is very safe and very effective. In Message 2, this statement was followed by a comparison of the COVID-19 vaccine to the flu shot and an explicit recommendation ("I recommend that you get it").	Participants were randomized to receive version #3 of 5 different versions of a message from a physician regarding vaccination. All messages included a statement that the vaccine is very safe and very effective. In Message 3, this statement was followed by a statement that millions of people have already received the COVID-19 vaccine and an explicit recommendation ("I recommend that you get it").	Participants were randomized to receive version #4 of 5 different versions of a message from a physician regarding vaccination. All messages included a statement that the vaccine is very safe and very effective. In Message 4, this statement was followed by an acknowledgment of concerns and reassurance that the physician personally reviewed the safety data and an explicit recommendation ("I recommend that you get it").	Participants were randomized to receive version #5 of 5 different versions of a message from a physician regarding vaccination. All messages included a statement that the vaccine is very safe and very effective. In Message 5, this statement was followed by an emphasis on protecting others an explicit recommendation ("I recommend that you get it").
Measure Participants	172	121	164	145	150
Count of Participants [Participants]	23 13.4%	26 21.5%	43 26.2%	35 24.1%	40 26.7%

Adverse Events

Adverse Event Reporting Description	All-Cause Mortality, Serious, and Other (Not Including Serious) Adverse Events were not monitored/assessed.
Arm/Group Title	Message 1		Message 2		Message 3		Message 4		Message 5
Arm/Group Description	Participants were randomized to receive version #1 of 5 different versions of a message from a physician regarding the COVID-19 vaccination. All messages included a statement that the vaccine is very safe and very effective. In Message 1, this statement was followed by a participatory-style recommendation ("What do you think?")		Participants were randomized to receive version #2 of 5 different versions of a message from a physician regarding vaccination. All messages included a statement that the vaccine is very safe and very effective. In Message 2, this statement was followed by a comparison of the COVID-19 vaccine to the flu shot and an explicit recommendation ("I recommend that you get it").		Participants were randomized to receive version #3 of 5 different versions of a message from a physician regarding vaccination. All messages included a statement that the vaccine is very safe and very effective. In Message 3, this statement was followed by a statement that millions of people have already received the COVID-19 vaccine and an explicit recommendation ("I recommend that you get it").		Participants were be randomized to receive version #4 of 5 different versions of a message from a physician regarding vaccination. All messages included a statement that the vaccine is very safe and very effective. In Message 4, this statement was followed by an acknowledgment of concerns and reassurance that the physician personally reviewed the safety data and an explicit recommendation ("I recommend that you get it").		Participants were randomized to receive version #5 of 5 different versions of a message from a physician regarding vaccination. All messages included a statement that the vaccine is very safe and very effective. In Message 5, this statement was followed by an emphasis on protecting others an explicit recommendation ("I recommend that you get it").
All Cause Mortality
	Message 1		Message 2		Message 3		Message 4		Message 5
	Affected / at Risk (%)	# Events	Affected / at Risk (%)	# Events	Affected / at Risk (%)	# Events	Affected / at Risk (%)	# Events	Affected / at Risk (%)	# Events
Total	0/0 (NaN)		0/0 (NaN)		0/0 (NaN)		0/0 (NaN)		0/0 (NaN)
Serious Adverse Events
	Message 1		Message 2		Message 3		Message 4		Message 5
	Affected / at Risk (%)	# Events	Affected / at Risk (%)	# Events	Affected / at Risk (%)	# Events	Affected / at Risk (%)	# Events	Affected / at Risk (%)	# Events
Total	0/0 (NaN)		0/0 (NaN)		0/0 (NaN)		0/0 (NaN)		0/0 (NaN)
Other (Not Including Serious) Adverse Events
	Message 1		Message 2		Message 3		Message 4		Message 5
	Affected / at Risk (%)	# Events	Affected / at Risk (%)	# Events	Affected / at Risk (%)	# Events	Affected / at Risk (%)	# Events	Affected / at Risk (%)	# Events
Total	0/0 (NaN)		0/0 (NaN)		0/0 (NaN)		0/0 (NaN)		0/0 (NaN)

Limitations/Caveats

Limitations include: (1) Inability to assess whether the impact of physician messages in practice would parallel the impact in the hypothetical scenarios used in this study; (2) The use of an online research platform (prolific.co) may limit generalizability of results.

More Information

Certain Agreements

All Principal Investigators ARE employed by the organization sponsoring the study.

There is NOT an agreement between Principal Investigators and the Sponsor (or its agents) that restricts the PI's rights to discuss or publish trial results after the trial is completed.