Trial Outcomes & Findings for COVID-19 Vaccinations With a Sweepstakes (NCT NCT04951310)

NCT ID: NCT04951310

Last Updated: 2025-02-03

Results Overview

The primary outcome is the weekly vaccinations (per 100k residents) for residents receiving a first dose of a COVID-19 vaccination in each zip/county/city, relative to the control group. The vaccination data was measured by local health departments and the residency data was measured by the U.S. Census. The investigators included data from 5 weeks of pre-intervention, 6 weeks of intervention, and 4 weeks of post-intervention. Weekly Vaccinations per 100k Residents = 100,000 \* Total residents receiving a first dose that week / Total residents in that zip/county/city code as measured by the Census or other official sources, at the most recent date available for all geographies of interest.

Recruitment status

COMPLETED

Study phase

NA

Target enrollment

3827656 participants

Primary outcome timeframe

15 Weeks

Results posted on

2025-02-03

Participant Flow

For our sweepstakes cash prizes, selected ZIP Codes with a high selection of cash prize winners (12 residents in each drawing) were 19126, 19133, and 19142 during Periods 1, 2, and 3, respectively.

Participant milestones

Participant milestones
Measure
Control
No Intervention: Control participants (residents of Bucks County, Montgomery County, Delaware County, and Allegheny County, PA) are not eligible for the sweepstakes.
Selected Zip Code Treatment
For our sweepstakes cash prizes, selected ZIP Codes with a high selection of cash prize winners (12 residents in each drawing) were 19126, 19133, and 19142 during Periods 1, 2, and 3, respectively.
All Other Philadelphia Residents Treatment
Philadelphia has 46 residential zip codes. During each treatment period one of these zip codes was randomly chosen to be the selected zip code. The other 43 zip codes were therefore in the All other Philadelphia Residents Treatment.
First Treatment Period (6/7/21-6/20/21)
STARTED
2585846
52874
1188936
First Treatment Period (6/7/21-6/20/21)
COMPLETED
2585846
52874
1188936
First Treatment Period (6/7/21-6/20/21)
NOT COMPLETED
0
0
0
Second Treatment Period (6/21/21-7/5/21)
STARTED
2585846
52874
1188936
Second Treatment Period (6/21/21-7/5/21)
COMPLETED
2585846
52874
1188936
Second Treatment Period (6/21/21-7/5/21)
NOT COMPLETED
0
0
0
Third Treatment Period (7/6/21-7/19/21)
STARTED
2585846
52874
1188936
Third Treatment Period (7/6/21-7/19/21)
COMPLETED
2585846
52874
1188936
Third Treatment Period (7/6/21-7/19/21)
NOT COMPLETED
0
0
0

Reasons for withdrawal

Withdrawal data not reported

Baseline Characteristics

As the analysis population was all residents in target Philadelphia zip codes, demographic information including age was not available to investigators and was not collected as a part of this study.

Baseline characteristics by cohort

Baseline characteristics by cohort
Measure
Control
n=2585846 Participants
No Intervention: Control participants (residents of Bucks County, Montgomery County, Delaware County, and Allegheny County, PA) are not eligible for the sweepstakes.
Selected Zip Code Treatment
n=52874 Participants
A total of 36 vaccinated Philadelphians won three cash prize packages, distributed from the total cash pool. These 36 were chosen over three drawings (i.e. treatment periods), with 12 residents chosen in each drawing. Selected Zip Code Treatment participants won half of these prizes and therefore had a significantly greater chance to win a prize in the sweepstakes than all other Philadelphia residents. A total of three zip codes were selected over the course of the Philly Vax Sweepstakes, one during each of the three treatment periods (19126 during period 1, 19133 during period 2, 19142 during period 3).
All Other Philadelphia Residents Treatment
n=1188936 Participants
Philadelphia has 46 residential zip codes. During each treatment period one of these zip codes was randomly chosen to be the selected zip code. The other 43 zip codes were therefore in the All Other Philadelphia Residents Treatment.
Total
n=3827656 Participants
Total of all reporting groups
Age, Customized
0 Participants
As the analysis population was all residents in target Philadelphia zip codes, demographic information including age was not available to investigators and was not collected as a part of this study.
Race and Ethnicity Not Collected
0 Participants
Race and Ethnicity were not collected from any participant.
Region of Enrollment
United States
2585846 participants
n=2585846 Participants
52874 participants
n=52874 Participants
1188936 participants
n=1188936 Participants
3827656 participants
n=3827656 Participants

PRIMARY outcome

Timeframe: 15 Weeks

The primary outcome is the weekly vaccinations (per 100k residents) for residents receiving a first dose of a COVID-19 vaccination in each zip/county/city, relative to the control group. The vaccination data was measured by local health departments and the residency data was measured by the U.S. Census. The investigators included data from 5 weeks of pre-intervention, 6 weeks of intervention, and 4 weeks of post-intervention. Weekly Vaccinations per 100k Residents = 100,000 \* Total residents receiving a first dose that week / Total residents in that zip/county/city code as measured by the Census or other official sources, at the most recent date available for all geographies of interest.

Outcome measures

Outcome measures
Measure
Control
n=2585846 Participants
No Intervention: Control participants (residents of Bucks County, Montgomery County, Delaware County, and Allegheny County, PA) are not eligible for the sweepstakes.
Selected Zip Code Treatment
n=52874 Participants
A total of 36 vaccinated Philadelphians won three cash prize packages, distributed from the total cash pool. These 36 were chosen over three drawings (i.e. treatment periods), with 12 residents chosen in each drawing. Selected Zip Code Treatment participants won half of these prizes and therefore had a significantly greater chance to win a prize in the sweepstakes than all other Philadelphia residents. A total of three zip codes were selected over the course of the Philly Vax Sweepstakes, one during each of the three treatment periods (19126 during period 1, 19133 during period 2, 19142 during period 3).
All Other Philadelphia Residents Treatment
n=1188936 Participants
Philadelphia has 46 residential zip codes. During each treatment period one of these zip codes was randomly chosen to be the selected zip code. The other 43 zip codes were therefore in the All Other Philadelphia Residents Treatment.
Weekly Vaccinations Per 100k Residents
0 Weekly Vaccinations per 100k Residents
-4 Weekly Vaccinations per 100k Residents
383 Weekly Vaccinations per 100k Residents

Adverse Events

Control

Serious events: 0 serious events
Other events: 0 other events
Deaths: 0 deaths

Selected Zip Code Treatment

Serious events: 0 serious events
Other events: 0 other events
Deaths: 0 deaths

All Other Philadelphia Residents Treatment

Serious events: 0 serious events
Other events: 0 other events
Deaths: 0 deaths

Serious adverse events

Adverse event data not reported

Other adverse events

Adverse event data not reported

Additional Information

Dr. Katherine Milkman

University of Pennsylvania

Phone: 215-573-9646

Results disclosure agreements

  • Principal investigator is a sponsor employee
  • Publication restrictions are in place