Longitudinal COVID-19 Antibody Testing in Indiana University Undergraduate Students

• Sponsor: Indiana University (Other)
• Overall Status: Completed
• CT.gov ID: NCT04620798
• Collaborator: (none)
• Enrollment: 1,076
• Location: 1
• Arms: 2
• Actual Duration (Months): 1.9
• Patients Per Site Per Month: 564.7

Study Details

Study Description

Brief Summary

The primary goal for this study is to assess whether receiving the results of an antibody test changes protective behavior to avoid SARS-CoV-2 infections (i.e., mask-wearing, physical distancing, limiting close contacts/avoiding crowds, hand-washing, avoiding contact with high-risk individuals). While studies have been published on the cross-sectional relationship between risk perception and other demographic characteristics and health behaviors that are protective for SARS-CoV-2 infection (see citations), there have been no studies showing the effect of receiving information about antibody positivity on protective behavior. Not only can results from this study be used to better model transmission, a better understanding of college student's risk perception around SARS-CoV-2 infections has implications for future vaccination strategies as well. There are concerns that a desire to return to "normal" life in combination with reduced perception of risk could have negative consequences for uptake of vaccination (Johns Hopkins Center for Health Security 2020 report, The Public's Role in COVID-19 Vaccination: Planning Recommendations Informed by Design Thinking and the Social, Behavioral, and Communication Sciences).

The antibody test used in this study is named 'SARS-CoV-2 IgM/IgG rapid assay kit (Colloidal Gold)'. It provides a fast, on-site, and accurate detection of IgM/IgG antibodies against SARS-CoV-2, with positive results of IgM antibodies indicating a recent infection, while positive results of IgG antibodies signaling a longer or previous infection. It can detect IgM and IgG antibodies against SARS-CoV-2 in human specimens of serum, plasma, or venous whole blood.

Condition or Disease	Intervention/Treatment	Phase
SARS-CoV-2; Serology; Students	Behavioral: Immediate vs. delayed provision of antibody test results	N/A

Detailed Description

This study will take place between September - November, 2020, and will ask participants to participate in: a web-based baseline survey, two rounds of SARS-CoV-2 serological testing (September and November), and bi-weekly web-based behavioral surveys (4 total surveys). Each is described in more detail below:

Web-based baseline survey: The baseline survey is designed to collect data on participant demographics, SARS-CoV-2 protective behaviors, alcohol drinking habits, nicotine use, and personality profile and should take less than 30 minutes to fill out. Participants who provide informed consent will be provided the link to the survey which they can fill out at a time convenient to them prior to first round of serological testing.

SARS-CoV-2 serological testing: There will be two rounds of SARS-CoV-2 serological testing, once at baseline (September 14-23) and once at endline (November 9-11). The serological testing visits will involve in-person laboratory testing for SARS-CoV-2 antibodies. The laboratory test involves a fingerstick to provide a small blood sample for the antibody test kits.

Antibody test results will eventually be provided to all study participants via secure link sent by email. With this message, we will include a clearly written information sheet about the chance for inaccurate test results and how it is still unknown whether previous infections confer immunity to future infections. We will clearly counsel participants to not use the results of the tests as proof of a previous SARS-CoV-2 infection, nor as a reason to change their behaviors. If participants wish to participate in the study, but do not wish to be provided with their antibody test results, they will be able to opt out of the results provision. If any participants opt out of receiving their test results, these participants would essentially create a third category of respondents: those who do not receive their results at all. However, these participants will still be analyzed with the trial arm to which they were randomized (intent to treat analysis).

The primary experiment will assess whether provision of the antibody test results leads to behavior change with respect to personal protective behaviors. To that end, all participants will be randomized to a trial arm that immediately receive results (within 24 hours) or a trial arm with a delayed provision of results (after 4 weeks). So as to not incentivize early drop-out, if a participant in the delayed results arm drops out early, they will still be provided their test results at the regularly scheduled time, not earlier. All other procedures between arms are identical. The endline laboratory test results will be delivered to all participants in the same timeframe - within 24-72 hours. The early and delayed test result intervention will have completed after the first round of testing.

Web-based behavioral surveys: To assess whether or not the provision of antibody test results changes behaviors, participants will self-reported behaviors in a short web-based survey every two weeks under observation. Links to these surveys will be sent to participants at regular bi-weekly intervals. Participants will fill out these short follow-up surveys on their computers or mobile devices. They are designed to take about 5 minutes or less to complete for each survey.

Study Design

• Study Type: Interventional
• Actual Enrollment: 1076 participants
• Allocation: Randomized
• Intervention Model: Parallel Assignment
• Intervention Model Description: Participants will be randomized to receive their antibody test results either within a day of the test or after a four-week waiting period in order to assess whether receiving the results of an antibody test changes protective behavior to avoid SARS-CoV-2 infections.Participants will be randomized to receive their antibody test results either within a day of the test or after a four-week waiting period in order to assess whether receiving the results of an antibody test changes protective behavior to avoid SARS-CoV-2 infections.
• Masking: Double (Participant, Investigator)
• Masking Description: Because we are attempting to assess the impact of having knowledge about a participants' antibody test result on their engagement in protective behaviors to avoid SARS-CoV-2 infections, the intervention information will be masked from the participant and the investigators.
• Primary Purpose: Screening
• Official Title: Longitudinal COVID-19 Antibody Testing in Indiana University Undergraduate Students
• Actual Study Start Date: Sep 14, 2020
• Actual Primary Completion Date: Nov 11, 2020
• Actual Study Completion Date: Nov 11, 2020

Arms and Interventions

Arm	Intervention/Treatment
Experimental: Intervention Participants will be given their results of their antibody test immediately (within 24 hours) and will be followed and surveyed to see if having this knowledge changes their engagement with SARS-CoV-2 prevention behaviors.	Behavioral: Immediate vs. delayed provision of antibody test results; The primary experiment will be assessing whether provision of the antibody test results leads to behavior change with respect to personal protective behaviors. To that end, we will randomize all participants to a trial arm that immediately receive results (within 24 hours) or a trial arm with a delayed provision of results (after 4 weeks).
No Intervention: Control (Delayed) Participants will be given their results of their antibody test after 4 weeks. Their engagement with SARS-CoV-2 prevention behaviors will also be assessed following testing.

Outcome Measures

Primary Outcome Measures

1. Frequency of Handwashing [2 weeks after the baseline antibody test]

   This outcome was dichotomized into Always and Very Often versus Sometimes, Rarely, and Never. It will be self-reported in a web-based follow-up survey administered at 2 weeks after the baseline antibody test, with an item adapted from the WHO 2020 "Monitoring knowledge, risk perceptions, preventive behaviours and trust to inform pandemic outbreak response": "During the last 7 days, which of the following measures have you taken to prevent infection from COVID-19?" -Frequently washed my hands with soap and water for at least 20 seconds Response options are: Always, Very Often, Sometimes, Rarely, Never

2. Frequency of Face Touching [2 weeks after the baseline antibody test]

   This outcome was dichotomized into Always and Very Often versus Sometimes, Rarely, and Never. This outcome will be self-reported in a web-based follow-up survey administered at 2 weeks after the baseline antibody test, with an item adapted from the WHO 2020 "Monitoring knowledge, risk perceptions, preventive behaviours and trust to inform pandemic outbreak response": "During the last 7 days, which of the following measures have you taken to prevent infection from COVID-19?" -Avoided touching my eyes, nose and mouth with unwashed hands Response options are: Always, Very Often, Sometimes, Rarely, Never

3. Frequency of Hand Sanitizer Use [2 weeks after the baseline antibody test]

   This outcome was dichotomized into Always and Very Often versus Sometimes, Rarely, and Never. This outcome will be self-reported in a web-based follow-up survey administered at 2 weeks after the baseline antibody test, with an item adapted from the WHO 2020 "Monitoring knowledge, risk perceptions, preventive behaviours and trust to inform pandemic outbreak response": "During the last 7 days, which of the following measures have you taken to prevent infection from COVID-19?" -Used disinfectants or hand sanitizer to clean hands when soap and water were not available Response options are: Always, Very Often, Sometimes, Rarely, Never

4. Frequency of Social Event Avoidance [2 weeks after the baseline antibody test]

   This outcome was dichotomized into Always and Very Often versus Sometimes, Rarely, and Never. It will be self-reported in a web-based follow-up survey administered at 2 weeks after the baseline antibody test, with an item adapted from the WHO 2020 "Monitoring knowledge, risk perceptions, preventive behaviours and trust to inform pandemic outbreak response": "During the last 7 days, which of the following measures have you taken to prevent infection from COVID-19?" -Avoided a social event I wanted to attend Response options are: Always, Very Often, Sometimes, Rarely, Never

5. Frequency of Staying Home From Work/School [2 weeks after the baseline antibody test]

   This outcome is dichotomized into Always and Very Often versus Sometimes, Rarely, and Never. It will be self-reported in a web-based follow-up survey administered at 2 weeks after the baseline antibody test, with an item adapted from the WHO 2020 "Monitoring knowledge, risk perceptions, preventive behaviours and trust to inform pandemic outbreak response": "During the last 7 days, which of the following measures have you taken to prevent infection from COVID-19?" -Stayed at home from work/school Response options are: Always, Very Often, Sometimes, Rarely, Never

6. Frequency of Mask Wearing [2 weeks after the baseline antibody test]

   This outcome is dichotomized into Always versus Very Often, Sometimes, Rarely, and Never. It will be self-reported in a web-based follow-up survey administered at 2 weeks after the baseline antibody test, with an item adapted from the WHO 2020 "Monitoring knowledge, risk perceptions, preventive behaviours and trust to inform pandemic outbreak response": "During the last 7 days, which of the following measures have you taken to prevent infection from COVID-19?" -Wore a mask in public Response options are: Always, Very Often, Sometimes, Rarely, Never

7. Frequency of Physical Distancing [2 weeks after the baseline antibody test]

   This outcome is dichotomized into Always and Very Often versus Sometimes, Rarely, and Never. It will be self-reported in a web-based follow-up survey administered at 2 weeks after the baseline antibody test, with an item adapted from the WHO 2020 "Monitoring knowledge, risk perceptions, preventive behaviours and trust to inform pandemic outbreak response": "During the last 7 days, which of the following measures have you taken to prevent infection from COVID-19?" -Ensured physical distancing in public Response options are: Always, Very Often, Sometimes, Rarely, Never

8. Frequency of Avoiding People at High-risk for Severe COVID-19 Infections [2 weeks after the baseline antibody test]

   This outcome was dichotomized into Always and Very Often versus Sometimes, Rarely, and Never. This outcome will be self-reported in a web-based follow-up survey administered at 2 weeks after the baseline antibody test, with an item adapted from the WHO 2020 "Monitoring knowledge, risk perceptions, preventive behaviours and trust to inform pandemic outbreak response": "During the last 7 days, which of the following measures have you taken to prevent infection from COVID-19?" -Avoided contact with people at high-risk for severe COVID-19 infections Response options are: Always, Very Often, Sometimes, Rarely, Never

Secondary Outcome Measures

1. Count of Participants With SARS-CoV-2 Seroconversion Over 8 Weeks [Approximately 8 weeks from baseline antibody test.]

   This outcome will be assessed by comparing SARS-CoV-2 serostatus at baseline (September 2020) and endline (November 2020). Those who were antibody negative at baseline but antibody positive at endline will be considered seroconverters in this study.

Eligibility Criteria

Criteria

• Ages Eligible for Study: 18 Years to 100 Years
• Sexes Eligible for Study: All
• Accepts Healthy Volunteers: Yes

Inclusion Criteria:

• Age 18 years or older

• Current IU undergraduate student

• Current resident of Monroe County, Indiana

Exclusion Criteria:

• Younger than 18 years old

• Current residence outside of Monroe County, Indiana

Contacts and Locations

Locations

	Site	City	State	Country	Postal Code
1	Indiana University	Bloomington	Indiana	United States	47405

Sponsors and Collaborators

• Indiana University

Investigators

• Principal Investigator: Molly Rosenberg, PhD, Indiana University Department of Epidemiology and Biostatistics

Study Documents (Full-Text)

• Study Protocol and Statistical Analysis Plan - Sep 1, 2020
• Informed Consent Form - Sep 1, 2020

More Information

Publications

None provided.

• Responsible Party: Molly Rosenberg, Assistant Professor Public Health, Indiana University
• ClinicalTrials.gov Identifier: NCT04620798
• Other Study ID Numbers: 2008293852
• First Posted: Nov 9, 2020
• Last Update Posted: Jan 31, 2022
• Last Verified: Jan 1, 2022

• Individual Participant Data (IPD) Sharing Statement: Yes
• Plan to Share IPD: Yes
• Studies a U.S. FDA-regulated Drug Product: No
• Studies a U.S. FDA-regulated Device Product: No
• Additional relevant MeSH terms: Antibodies

Study Results

Participant Flow

Recruitment Details

We randomly sampled 7,499 students from the sampling frame of all IU Bloomington undergraduates enrolled at the beginning of the Fall 2020 semester. Students in the sample were eligible to participate if they were (1) aged 18 years or older, (2) a current IU Bloomington undergraduate student, and (3) currently residing in Monroe County, Indiana. Of those sampled, 4,069 potential participants met the inclusion criteria for the study and were contacted by email with a study invitation.

Pre-assignment Detail

Following the study invitation, 1076 of the 4069 eligible sampled students were enrolled in the study and received randomization. 2651 students tacitly refused participation, 21 students explicitly refused participation or withdrew from the study, and 321 students missed the baseline study visit.

Arm/Group Title	Intervention (Immediate Results)	Control (Delayed Results)
Arm/Group Description	Participants will be given their results of their antibody test immediately (within 24 hours).	Participants will be given their results of their antibody test four weeks following the test.
Period Title: Overall Study
STARTED	536	540
Completed Behavioral Survey	477	508
COMPLETED	410	402
NOT COMPLETED	126	138

Baseline Characteristics

Arm/Group Title	Intervention (Immediate Results)	Control (Delayed Results)	Total
Arm/Group Description	Participants will be given their results of their antibody test immediately (within 24 hours).	Participants will be given their results of their antibody test four weeks following the test.	Total of all reporting groups
Overall Participants	536	540	1076
Age (Count of Participants)
<=18 years	0 0%	0 0%	0 0%
Between 18 and 65 years	508 94.8%	502 93%	1010 93.9%
>=65 years	0 0%	0 0%	0 0%
Age, Customized (Count of Participants)
18 years old	111 20.7%	97 18%	208 19.3%
19 years old	109 20.3%	115 21.3%	224 20.8%
20 years old	109 20.3%	119 22%	228 21.2%
21 years old	132 24.6%	123 22.8%	255 23.7%
22+ years old	47 8.8%	48 8.9%	95 8.8%
Missing	28 5.2%	38 7%	66 6.1%
Sex: Female, Male (Count of Participants)
Female	333 62.1%	356 65.9%	689 64%
Male	201 37.5%	181 33.5%	382 35.5%
Ethnicity (NIH/OMB) (Count of Participants)
Hispanic or Latino	39 7.3%	39 7.2%	78 7.2%
Not Hispanic or Latino	497 92.7%	501 92.8%	998 92.8%
Unknown or Not Reported	0 0%	0 0%	0 0%
Race (NIH/OMB) (Count of Participants)
American Indian or Alaska Native	0 0%	0 0%	0 0%
Asian	43 8%	37 6.9%	80 7.4%
Native Hawaiian or Other Pacific Islander	0 0%	0 0%	0 0%
Black or African American	6 1.1%	7 1.3%	13 1.2%
White	417 77.8%	430 79.6%	847 78.7%
More than one race	43 8%	42 7.8%	85 7.9%
Unknown or Not Reported	27 5%	24 4.4%	51 4.7%
Region of Enrollment (participants) [Number]
United States	536 100%	540 100%	1076 100%
Undergraduate School Year (Count of Participants)
First Year	123 22.9%	113 20.9%	236 21.9%
Second Year	119 22.2%	127 23.5%	246 22.9%
Third Year	127 23.7%	137 25.4%	264 24.5%
Fourth Year	154 28.7%	143 26.5%	297 27.6%
Fifth Year or More	10 1.9%	17 3.1%	27 2.5%
Missing	3 0.6%	3 0.6%	6 0.6%
Residence (Count of Participants)
On-Campus	176 32.8%	162 30%	338 31.4%
Off-Campus	358 66.8%	375 69.4%	733 68.1%
Missing	2 0.4%	3 0.6%	5 0.5%
Greek Affiliation Status (Count of Participants)
Yes	129 24.1%	129 23.9%	258 24%
No	403 75.2%	409 75.7%	812 75.5%
Missing	4 0.7%	2 0.4%	6 0.6%

Outcome Measures

1. Primary Outcome

Title	Frequency of Handwashing
Description	This outcome was dichotomized into Always and Very Often versus Sometimes, Rarely, and Never. It will be self-reported in a web-based follow-up survey administered at 2 weeks after the baseline antibody test, with an item adapted from the WHO 2020 "Monitoring knowledge, risk perceptions, preventive behaviours and trust to inform pandemic outbreak response": "During the last 7 days, which of the following measures have you taken to prevent infection from COVID-19?" -Frequently washed my hands with soap and water for at least 20 seconds Response options are: Always, Very Often, Sometimes, Rarely, Never
Time Frame	2 weeks after the baseline antibody test

Outcome Measure Data

Analysis Population Description

[Not Specified]

Arm/Group Title	Intervention (Immediate Results)	Control (Delayed Results)
Arm/Group Description	Participants will be given their results of their antibody test immediately (within 24 hours).	Participants will be given their results of their antibody test four weeks following the test.
Measure Participants	477	508
Always or Very Often	412 76.9%	432 80%
Never, Sometimes, or Rarely	65 12.1%	75 13.9%
Not Applicable	0 0%	1 0.2%

Statistical Analysis 1

Statistical Analysis Overview	Comparison Group Selection	Intervention (Immediate Results), Control (Delayed Results)
	Comments	This analysis includes only those participants with a negative antibody test result at baseline to test the association between the treatment condition (immediate vs. delayed test results) and behavioral outcomes. The reference group for this analysis was the control (delayed results) group.
	Type of Statistical Test	Superiority
	Comments
Statistical Test of Hypothesis	p-Value
	Comments
	Method
	Comments
Method of Estimation	Estimation Parameter	Risk Ratio (RR)
	Estimated Value	1.01
	Confidence Interval	(2-Sided) 95%; 0.96 to 1.07
	Parameter Dispersion	Type: Value:
	Estimation Comments	This analysis compares the probability of responding "Very Often/Always" vs. all other response categories. The reference group for this analysis was the control (delayed results) group.

Statistical Analysis 2

Statistical Analysis Overview	Comparison Group Selection	Intervention (Immediate Results), Control (Delayed Results)
	Comments	This analysis uses only those participants with a positive antibody test result at baseline to test the association between the treatment condition (immediate vs. delayed test results) and behavioral outcomes. The reference group for this analysis was the control (delayed results) group.
	Type of Statistical Test	Superiority
	Comments
Statistical Test of Hypothesis	p-Value
	Comments
	Method
	Comments
Method of Estimation	Estimation Parameter	Risk Ratio (RR)
	Estimated Value	1.05
	Confidence Interval	(2-Sided) 95%; 0.77 to 1.44
	Parameter Dispersion	Type: Value:
	Estimation Comments	This analysis compares the probability of responding "Very Often/Always" vs. all other response categories. The reference group for this analysis was the control (delayed results) group.

2. Primary Outcome

Title	Frequency of Face Touching
Description	This outcome was dichotomized into Always and Very Often versus Sometimes, Rarely, and Never. This outcome will be self-reported in a web-based follow-up survey administered at 2 weeks after the baseline antibody test, with an item adapted from the WHO 2020 "Monitoring knowledge, risk perceptions, preventive behaviours and trust to inform pandemic outbreak response": "During the last 7 days, which of the following measures have you taken to prevent infection from COVID-19?" -Avoided touching my eyes, nose and mouth with unwashed hands Response options are: Always, Very Often, Sometimes, Rarely, Never
Time Frame	2 weeks after the baseline antibody test

Outcome Measure Data

Analysis Population Description

[Not Specified]

Arm/Group Title	Intervention (Immediate Results)	Control (Delayed Results)
Arm/Group Description	Participants will be given their results of their antibody test immediately (within 24 hours).	Participants will be given their results of their antibody test four weeks following the test.
Measure Participants	476	507
Always or Very Often	280 52.2%	303 56.1%
Never, Sometimes, or Rarely	196 36.6%	204 37.8%

Statistical Analysis 1

Statistical Analysis Overview	Comparison Group Selection	Intervention (Immediate Results), Control (Delayed Results)
	Comments	This analysis includes only those participants with a negative antibody test result at baseline to test the association between the treatment condition (immediate vs. delayed test results) and behavioral outcomes. The reference group for this analysis was the control (delayed results) group.
	Type of Statistical Test	Superiority
	Comments
Statistical Test of Hypothesis	p-Value
	Comments
	Method
	Comments
Method of Estimation	Estimation Parameter	Risk Ratio (RR)
	Estimated Value	0.99
	Confidence Interval	(2-Sided) 95%; 0.89 to 1.10
	Parameter Dispersion	Type: Value:
	Estimation Comments	This analysis compares the probability of responding "Very Often/Always" vs. all other response categories. The reference group for this analysis was the control (delayed results) group.

Statistical Analysis 2

Statistical Analysis Overview	Comparison Group Selection	Intervention (Immediate Results), Control (Delayed Results)
	Comments	This analysis uses only those participants with a positive antibody test result at baseline to test the association between the treatment condition (immediate vs. delayed test results) and behavioral outcomes. The reference group for this analysis was the control (delayed results) group.
	Type of Statistical Test	Superiority
	Comments
Statistical Test of Hypothesis	p-Value
	Comments
	Method
	Comments
Method of Estimation	Estimation Parameter	Risk Ratio (RR)
	Estimated Value	0.90
	Confidence Interval	(2-Sided) 95%; 0.50 to 1.62
	Parameter Dispersion	Type: Value:
	Estimation Comments	This analysis compares the probability of responding "Very Often/Always" vs. all other response categories. The reference group for this analysis was the control (delayed results) group.

3. Primary Outcome

Title	Frequency of Hand Sanitizer Use
Description	This outcome was dichotomized into Always and Very Often versus Sometimes, Rarely, and Never. This outcome will be self-reported in a web-based follow-up survey administered at 2 weeks after the baseline antibody test, with an item adapted from the WHO 2020 "Monitoring knowledge, risk perceptions, preventive behaviours and trust to inform pandemic outbreak response": "During the last 7 days, which of the following measures have you taken to prevent infection from COVID-19?" -Used disinfectants or hand sanitizer to clean hands when soap and water were not available Response options are: Always, Very Often, Sometimes, Rarely, Never
Time Frame	2 weeks after the baseline antibody test

Outcome Measure Data

Analysis Population Description

[Not Specified]

Arm/Group Title	Intervention (Immediate Results)	Control (Delayed Results)
Arm/Group Description	Participants will be given their results of their antibody test immediately (within 24 hours).	Participants will be given their results of their antibody test four weeks following the test.
Measure Participants	477	505
Always or Very Often	414 77.2%	436 80.7%
Never, Sometimes, or Rarely	60 11.2%	69 12.8%
Not Applicable	3 0.6%	0 0%

Statistical Analysis 1

Statistical Analysis Overview	Comparison Group Selection	Intervention (Immediate Results), Control (Delayed Results)
	Comments	This analysis includes only those participants with a negative antibody test result at baseline to test the association between the treatment condition (immediate vs. delayed test results) and behavioral outcomes. The reference group for this analysis was the control (delayed results) group.
	Type of Statistical Test	Superiority
	Comments
Statistical Test of Hypothesis	p-Value
	Comments
	Method
	Comments
Method of Estimation	Estimation Parameter	Risk Ratio (RR)
	Estimated Value	1.01
	Confidence Interval	(2-Sided) 95%; 0.96 to 1.06
	Parameter Dispersion	Type: Value:
	Estimation Comments	This analysis compares the probability of responding "Very Often/Always" vs. all other response categories. The reference group for this analysis was the control (delayed results) group.

Statistical Analysis 2

Statistical Analysis Overview	Comparison Group Selection	Intervention (Immediate Results), Control (Delayed Results)
	Comments	This analysis uses only those participants with a positive antibody test result at baseline to test the association between the treatment condition (immediate vs. delayed test results) and behavioral outcomes. The reference group for this analysis was the control (delayed results) group.
	Type of Statistical Test	Superiority
	Comments
Statistical Test of Hypothesis	p-Value
	Comments
	Method
	Comments
Method of Estimation	Estimation Parameter	Risk Ratio (RR)
	Estimated Value	0.98
	Confidence Interval	(2-Sided) 95%; 0.74 to 1.31
	Parameter Dispersion	Type: Value:
	Estimation Comments	This analysis compares the probability of responding "Very Often/Always" vs. all other response categories. The reference group for this analysis was the control (delayed results) group.

4. Primary Outcome

Title	Frequency of Social Event Avoidance
Description	This outcome was dichotomized into Always and Very Often versus Sometimes, Rarely, and Never. It will be self-reported in a web-based follow-up survey administered at 2 weeks after the baseline antibody test, with an item adapted from the WHO 2020 "Monitoring knowledge, risk perceptions, preventive behaviours and trust to inform pandemic outbreak response": "During the last 7 days, which of the following measures have you taken to prevent infection from COVID-19?" -Avoided a social event I wanted to attend Response options are: Always, Very Often, Sometimes, Rarely, Never
Time Frame	2 weeks after the baseline antibody test

Outcome Measure Data

Analysis Population Description

[Not Specified]

Arm/Group Title	Intervention (Immediate Results)	Control (Delayed Results)
Arm/Group Description	Participants will be given their results of their antibody test immediately (within 24 hours).	Participants will be given their results of their antibody test four weeks following the test.
Measure Participants	477	507
Always or Very Often	209 39%	236 43.7%
Never, Rarely, or Sometimes	224 41.8%	228 42.2%
Not Applicable	44 8.2%	43 8%

Statistical Analysis 1

Statistical Analysis Overview	Comparison Group Selection	Intervention (Immediate Results), Control (Delayed Results)
	Comments	This analysis includes only those participants with a negative antibody test result at baseline to test the association between the treatment condition (immediate vs. delayed test results) and behavioral outcomes. The reference group for this analysis was the control (delayed results) group.
	Type of Statistical Test	Superiority
	Comments
Statistical Test of Hypothesis	p-Value
	Comments
	Method
	Comments
Method of Estimation	Estimation Parameter	Risk Ratio (RR)
	Estimated Value	0.96
	Confidence Interval	(2-Sided) 95%; 0.84 to 1.09
	Parameter Dispersion	Type: Value:
	Estimation Comments	This analysis compares the probability of responding "Very Often/Always" vs. all other response categories. The reference group for this analysis was the control (delayed results) group.

Statistical Analysis 2

Statistical Analysis Overview	Comparison Group Selection	Intervention (Immediate Results), Control (Delayed Results)
	Comments	This analysis uses only those participants with a positive antibody test result at baseline to test the association between the treatment condition (immediate vs. delayed test results) and behavioral outcomes. The reference group for this analysis was the control (delayed results) group.
	Type of Statistical Test	Superiority
	Comments
Statistical Test of Hypothesis	p-Value
	Comments
	Method
	Comments
Method of Estimation	Estimation Parameter	Risk Ratio (RR)
	Estimated Value	0.75
	Confidence Interval	(2-Sided) 95%; 0.33 to 1.72
	Parameter Dispersion	Type: Value:
	Estimation Comments	This analysis compares the probability of a response of "Very Often/Always" vs. all other response categories. The reference group for this analysis was the control (delayed results) group.

5. Primary Outcome

Title	Frequency of Staying Home From Work/School
Description	This outcome is dichotomized into Always and Very Often versus Sometimes, Rarely, and Never. It will be self-reported in a web-based follow-up survey administered at 2 weeks after the baseline antibody test, with an item adapted from the WHO 2020 "Monitoring knowledge, risk perceptions, preventive behaviours and trust to inform pandemic outbreak response": "During the last 7 days, which of the following measures have you taken to prevent infection from COVID-19?" -Stayed at home from work/school Response options are: Always, Very Often, Sometimes, Rarely, Never
Time Frame	2 weeks after the baseline antibody test

Outcome Measure Data

Analysis Population Description

[Not Specified]

Arm/Group Title	Intervention (Immediate Results)	Control (Delayed Results)
Arm/Group Description	Participants will be given their results of their antibody test immediately (within 24 hours).	Participants will be given their results of their antibody test four weeks following the test.
Measure Participants	477	506
Always or Very Often	152 28.4%	185 34.3%
Never, Rarely, or Sometimes	254 47.4%	255 47.2%
Not Applicable	71 13.2%	66 12.2%

Statistical Analysis 1

Statistical Analysis Overview	Comparison Group Selection	Intervention (Immediate Results), Control (Delayed Results)
	Comments	This analysis includes only those participants with a negative antibody test result at baseline to test the association between the treatment condition (immediate vs. delayed test results) and behavioral outcomes. The reference group for this analysis was the control (delayed results) group.
	Type of Statistical Test	Superiority
	Comments
Statistical Test of Hypothesis	p-Value
	Comments
	Method
	Comments
Method of Estimation	Estimation Parameter	Risk Ratio (RR)
	Estimated Value	0.87
	Confidence Interval	(2-Sided) 95%; 0.74 to 1.04
	Parameter Dispersion	Type: Value:
	Estimation Comments	This analysis compares the probability of responding "Very Often/Always" vs. all other response categories. The reference group for this analysis was the control (delayed results) group.

Statistical Analysis 2

Statistical Analysis Overview	Comparison Group Selection	Intervention (Immediate Results), Control (Delayed Results)
	Comments	This analysis uses only those participants with a positive antibody test result at baseline to test the association between the treatment condition (immediate vs. delayed test results) and behavioral outcomes. The reference group for this analysis was the control (delayed results) group.
	Type of Statistical Test	Superiority
	Comments
Statistical Test of Hypothesis	p-Value
	Comments
	Method
	Comments
Method of Estimation	Estimation Parameter	Risk Ratio (RR)
	Estimated Value	1.40
	Confidence Interval	(2-Sided) 95%; 0.60 to 3.25
	Parameter Dispersion	Type: Value:
	Estimation Comments	This analysis compares the probability of a response of "Very Often/Always" vs. all other response categories. The reference group for this analysis was the control (delayed results) group.

6. Primary Outcome

Title	Frequency of Mask Wearing
Description	This outcome is dichotomized into Always versus Very Often, Sometimes, Rarely, and Never. It will be self-reported in a web-based follow-up survey administered at 2 weeks after the baseline antibody test, with an item adapted from the WHO 2020 "Monitoring knowledge, risk perceptions, preventive behaviours and trust to inform pandemic outbreak response": "During the last 7 days, which of the following measures have you taken to prevent infection from COVID-19?" -Wore a mask in public Response options are: Always, Very Often, Sometimes, Rarely, Never
Time Frame	2 weeks after the baseline antibody test

Outcome Measure Data

Analysis Population Description

[Not Specified]

Arm/Group Title	Intervention (Immediate Results)	Control (Delayed Results)
Arm/Group Description	Participants will be given their results of their antibody test immediately (within 24 hours).	Participants will be given their results of their antibody test four weeks following the test.
Measure Participants	476	504
Always	400 74.6%	433 80.2%
Never, Rarely, Sometimes, or Very Often	76 14.2%	71 13.1%

Statistical Analysis 1

Statistical Analysis Overview	Comparison Group Selection	Intervention (Immediate Results), Control (Delayed Results)
	Comments	This analysis includes only those participants with a negative antibody test result at baseline to test the association between the treatment condition (immediate vs. delayed test results) and behavioral outcomes. The reference group for this analysis was the control (delayed results) group.
	Type of Statistical Test	Superiority
	Comments
Statistical Test of Hypothesis	p-Value
	Comments
	Method
	Comments
Method of Estimation	Estimation Parameter	Risk Ratio (RR)
	Estimated Value	1.01
	Confidence Interval	(2-Sided) 95%; 0.99 to 1.03
	Parameter Dispersion	Type: Value:
	Estimation Comments	This analysis compares the probability of a response of "Always" vs. all other response categories. The reference group for this analysis was the control (delayed results) group.

Statistical Analysis 2

Statistical Analysis Overview	Comparison Group Selection	Intervention (Immediate Results), Control (Delayed Results)
	Comments	This analysis uses only those participants with a positive antibody test result at baseline to test the association between the treatment condition (immediate vs. delayed test results) and behavioral outcomes. The reference group for this analysis was the control (delayed results) group.
	Type of Statistical Test	Superiority
	Comments
Statistical Test of Hypothesis	p-Value
	Comments
	Method
	Comments
Method of Estimation	Estimation Parameter	Risk Ratio (RR)
	Estimated Value	0.97
	Confidence Interval	(2-Sided) 95%; 0.77 to 1.21
	Parameter Dispersion	Type: Value:
	Estimation Comments	This analysis compares the probability of a response of "Always" vs. all other response categories. The reference group for this analysis was the control (delayed results) group.

7. Primary Outcome

Title	Frequency of Physical Distancing
Description	This outcome is dichotomized into Always and Very Often versus Sometimes, Rarely, and Never. It will be self-reported in a web-based follow-up survey administered at 2 weeks after the baseline antibody test, with an item adapted from the WHO 2020 "Monitoring knowledge, risk perceptions, preventive behaviours and trust to inform pandemic outbreak response": "During the last 7 days, which of the following measures have you taken to prevent infection from COVID-19?" -Ensured physical distancing in public Response options are: Always, Very Often, Sometimes, Rarely, Never
Time Frame	2 weeks after the baseline antibody test

Outcome Measure Data

Analysis Population Description

[Not Specified]

Arm/Group Title	Intervention (Immediate Results)	Control (Delayed Results)
Arm/Group Description	Participants will be given their results of their antibody test immediately (within 24 hours).	Participants will be given their results of their antibody test four weeks following the test.
Measure Participants	477	506
Always or Very Often	427 79.7%	452 83.7%
Never, Rarely, or Sometimes	50 9.3%	54 10%

Statistical Analysis 1

Statistical Analysis Overview	Comparison Group Selection	Intervention (Immediate Results), Control (Delayed Results)
	Comments	This analysis includes only those participants with a negative antibody test result at baseline to test the association between the treatment condition (immediate vs. delayed test results) and behavioral outcomes. The reference group for this analysis was the control (delayed results) group.
	Type of Statistical Test	Superiority
	Comments
Statistical Test of Hypothesis	p-Value
	Comments
	Method
	Comments
Method of Estimation	Estimation Parameter	Risk Ratio (RR)
	Estimated Value	1.01
	Confidence Interval	(2-Sided) 95%; 0.97 to 1.06
	Parameter Dispersion	Type: Value:
	Estimation Comments	This analysis compares the probability of a response of "Very Often/Always" vs. all other response categories. The reference group for this analysis was the control (delayed results) group.

Statistical Analysis 2

Statistical Analysis Overview	Comparison Group Selection	Intervention (Immediate Results), Control (Delayed Results)
	Comments	This analysis uses only those participants with a positive antibody test result at baseline to test the association between the treatment condition (immediate vs. delayed test results) and behavioral outcomes. The reference group for this analysis was the control (delayed results) group.
	Type of Statistical Test	Superiority
	Comments
Statistical Test of Hypothesis	p-Value
	Comments
	Method
	Comments
Method of Estimation	Estimation Parameter	Risk Ratio (RR)
	Estimated Value	0.82
	Confidence Interval	(2-Sided) 95%; 0.60 to 1.11
	Parameter Dispersion	Type: Value:
	Estimation Comments	This analysis compares the probability of a response of "Very Often/Always" vs. all other response categories. The reference group for this analysis was the control (delayed results) group.

8. Primary Outcome

Title	Frequency of Avoiding People at High-risk for Severe COVID-19 Infections
Description	This outcome was dichotomized into Always and Very Often versus Sometimes, Rarely, and Never. This outcome will be self-reported in a web-based follow-up survey administered at 2 weeks after the baseline antibody test, with an item adapted from the WHO 2020 "Monitoring knowledge, risk perceptions, preventive behaviours and trust to inform pandemic outbreak response": "During the last 7 days, which of the following measures have you taken to prevent infection from COVID-19?" -Avoided contact with people at high-risk for severe COVID-19 infections Response options are: Always, Very Often, Sometimes, Rarely, Never
Time Frame	2 weeks after the baseline antibody test

Outcome Measure Data

Analysis Population Description

[Not Specified]

Arm/Group Title	Intervention (Immediate Results)	Control (Delayed Results)
Arm/Group Description	Participants will be given their results of their antibody test immediately (within 24 hours).	Participants will be given their results of their antibody test four weeks following the test.
Measure Participants	477	507
Always or Very Often	433 80.8%	466 86.3%
Never, Sometimes, or Rarely	30 5.6%	31 5.7%
Not Applicable	14 2.6%	10 1.9%

Statistical Analysis 1

Statistical Analysis Overview	Comparison Group Selection	Intervention (Immediate Results), Control (Delayed Results)
	Comments	This analysis includes only those participants with a negative antibody test result at baseline to test the association between the treatment condition (immediate vs. delayed test results) and behavioral outcomes. The reference group for this analysis was the control (delayed results) group.
	Type of Statistical Test	Superiority
	Comments
Statistical Test of Hypothesis	p-Value
	Comments
	Method
	Comments
Method of Estimation	Estimation Parameter	Risk Ratio (RR)
	Estimated Value	1.00
	Confidence Interval	(2-Sided) 95%; 0.97 to 1.04
	Parameter Dispersion	Type: Value:
	Estimation Comments	This analysis compares the probability of responding "Very Often/Always" vs. all other response categories. The reference group for this analysis was the control (delayed results) group.

Statistical Analysis 2

Statistical Analysis Overview	Comparison Group Selection	Intervention (Immediate Results), Control (Delayed Results)
	Comments	This analysis uses only those participants with a positive antibody test result at baseline to test the association between the treatment condition (immediate vs. delayed test results) and behavioral outcomes. The reference group for this analysis was the control (delayed results) group.
	Type of Statistical Test	Superiority
	Comments
Statistical Test of Hypothesis	p-Value
	Comments
	Method
	Comments
Method of Estimation	Estimation Parameter	Risk Ratio (RR)
	Estimated Value	0.91
	Confidence Interval	(2-Sided) 95%; 0.74 to 1.12
	Parameter Dispersion	Type: Value:
	Estimation Comments	This analysis compares the probability of a response of "Very Often/Always" vs. all other response categories. The reference group for this analysis was the control (delayed results) group.

9. Secondary Outcome

Title	Count of Participants With SARS-CoV-2 Seroconversion Over 8 Weeks
Description	This outcome will be assessed by comparing SARS-CoV-2 serostatus at baseline (September 2020) and endline (November 2020). Those who were antibody negative at baseline but antibody positive at endline will be considered seroconverters in this study.
Time Frame	Approximately 8 weeks from baseline antibody test.

Outcome Measure Data

Analysis Population Description

[Not Specified]

Arm/Group Title	Intervention (Immediate Results)	Control (Delayed Results)
Arm/Group Description	Participants will be given their results of their antibody test immediately (within 24 hours).	Participants will be given their results of their antibody test four weeks following the test.
Measure Participants	406	402
Yes	20 3.7%	22 4.1%
No	386 72%	380 70.4%

Statistical Analysis 1

Statistical Analysis Overview	Comparison Group Selection	Intervention (Immediate Results), Control (Delayed Results)
	Comments	This analysis includes only those participants with a negative antibody test result at baseline to test the association between the treatment condition (immediate vs. delayed test results) and seroconversion. The reference group for this analysis was the control (delayed results) group.
	Type of Statistical Test	Superiority
	Comments
Statistical Test of Hypothesis	p-Value
	Comments
	Method
	Comments
Method of Estimation	Estimation Parameter	Risk Ratio (RR)
	Estimated Value	0.94
	Confidence Interval	(2-Sided) 95%; 0.52 to 1.71
	Parameter Dispersion	Type: Value:
	Estimation Comments	This analysis compares the probability of seroconverting during the study period. The reference group for this analysis was the control (delayed results) group.

Adverse Events

Time Frame	Eight weeks, from baseline antibody testing to endline antibody testing
Arm/Group Title	Intervention (Immediate Results)		Control (Delayed Results)
Arm/Group Description	Participants will be given their results of their antibody test immediately (within 24 hours).		Participants will be given their results of their antibody test four weeks following the test.
All Cause Mortality
	Intervention (Immediate Results)		Control (Delayed Results)
	Affected / at Risk (%)	# Events	Affected / at Risk (%)	# Events
Total	0/536 (0%)		0/540 (0%)
Serious Adverse Events
	Intervention (Immediate Results)		Control (Delayed Results)
	Affected / at Risk (%)	# Events	Affected / at Risk (%)	# Events
Total	0/536 (0%)		0/540 (0%)
Other (Not Including Serious) Adverse Events
	Intervention (Immediate Results)		Control (Delayed Results)
	Affected / at Risk (%)	# Events	Affected / at Risk (%)	# Events
Total	0/536 (0%)		0/540 (0%)

Limitations/Caveats

As results were disseminated by email, we cannot confirm that everyone in each treatment condition received their results on the expected schedule, or at all. However, operational and survey data we collected indicated that participants received their test results at similar rates in both arms, alleviating concerns of differential intervention uptake.

More Information

Certain Agreements

Principal Investigators are NOT 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.